Methods of providing direct blood flow between a heart chamber and a coronary vessel

ABSTRACT

Methodology and related medical devices for effectively bypassing a blocked or partially blocked coronary artery and providing oxygenated blood to the myocardium. A coronary artery bypass method utilizes a shunt member. An upstream end portion of the shunt member is disposed in the myocardium of a patient&#39;s heart so that the upstream end portion communicates with the left ventricle of the patient&#39;s heart. An opposite or downstream end portion of the shunt member is placed in communication with a coronary artery of the patient downstream of a blockage in the coronary artery. The shunt member extends into the coronary artery from the myocardium either directly or indirectly with an intermediate or middle portion of the shunt member being disposed in an intrapericardial space of the patient, outside of the myocardium and outside of the coronary artery. In a method for performing a myocardial revascularization a passageway is formed at least partially through a myocardium of a patient from an outer surface of the patient&#39;s heart, with a surgical operation being performed at an outer end of the passageway to permanently close the passageway at the outer end. The passageway may extend though a posterior wall of a coronary artery and is produced by forming an aperture in an anterior wall of the coronary artery and forming the passageway in substantial alignment with the aperture. The closure of the passageway is effectuated particularly by closing the aperture in the anterior wall of the coronary artery.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation of application Ser. No. 09/369,039, filed Aug. 4,1999, now abandoned and a continuation-in-part of application Ser. No.09/016,485, filed Jan. 30, 1998 now abandoned and a continuation-in-partof PCT application Ser. No. PCT/US99/03484, filed Feb. 17, 1999, andwhich claims the benefit of U.S. provisional application Nos. 60/099,691and 60/099,720, each filed Sep. 10, 1998; U.S. provisional applicationno. 60/099,767, filed Sep. 10, 1998; and U.S. provisional applicationno. 60/104,397, filed Oct. 15, 1998, all of which are incorporatedherein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to an apparatus and method for implanting aconduit to allow communication of fluids from one portion of a patient'sbody to another; and, more particularly, to a blood flow conduit toallow communication from a heart chamber to a vessel or vice versa,and/or vessel to vessel. Even more particularly, the invention relatesto a left ventricular conduit and related conduit configurations forcontrolling the flow of blood through the conduit to achieve bypass ofan occluded coronary artery.

2. Description of Related Art

Coronary artery disease is a major problem in the U.S. and throughoutthe world. In fact, about 1.1 million “open heart” procedures areperformed each year, and current estimates are that approximately 4.8million people suffer from some degree of congestive heart failure.

When coronary arteries or other blood vessels become clogged withplaque, the results are at the very least impairment of the efficiencyof the heart's pumping action. On the more severe side of the scale areheart attack and death. In some cases, clogged arteries can be unblockedthrough minimally invasive techniques such as balloon angioplasty. Inmore difficult cases, a surgical bypass of the blocked vessel isnecessary.

In a bypass operation, one or more arterial or venous segments areharvested from the body and then surgically inserted between the aortaand the coronary artery. The inserted vessel segments, or transplants,act as a bypass of the blocked portion of the coronary artery and thusprovide for a free or unobstructed flow of blood to the heart. More than500,000 bypass procedures are performed in the U.S. every year.

Coronary artery bypass grafting (CABG) has been used for more than 30years. Initially, the saphenous vein (SV) served as the principalconduit for coronary bypass, but studies over the last dozen years haveshown a 35–40% increase in 10-year patency rate for the internalthoracic artery (ITA) compared with the SV. The SV, in fact, has onlybeen shown to have a 10-year patency rate of 50%. Since the mid 1980's,not only the ITA, but also the alternative arterial conduits have beenincreasingly used. These conduits include the grastroepiploic artery(GEA), inferior epigastric artery (IEA), and radial artery (RA), whichhave been used primarily as supplements to both the right and left ITA.

Although the use of arterial conduits results in demonstrably betterlong-term patency, use of arteries in place of the SV often requirescomplex technical challenges, such as free grafts, sequentialanastomosis, and conduit-to-conduit anastomosis. Some of the reasons forthe difficulty in using arterial conduits reside in the fact that theyare much more fragile than the SV and therefore easier to damage, anddue to their smaller size, easier to occlude completely or partiallythrough technical error during grafting.

Such coronary artery bypass surgery, however, is a very intrusiveprocedure that is expensive, time-consuming and traumatic to thepatient. The operation requires an incision through the patient'ssternum (sternotomy), and the patient be placed on a bypass pump so thatthe heart can be operated on while not beating. A vein graft isharvested from the patient's leg, another highly invasive procedure, anda delicate surgical procedure is required to piece the bypass graft tothe coronary artery (anastomosis). Hospital stays subsequent to thesurgery and convalescence periods are prolonged.

As mentioned above, another conventional treatment is percutaneoustransluminal coronary angioplasty (PTCA) or other types of angioplasty.However, such vascular treatments are not always indicated due to thetype or location of the blockage, or due to the risk of the emboliformation.

One bypass technique employed in the prior art is taught by Wilk (U.S.Pat. Nos. 5,287,861, 5,409,019, 5,662,124, and 5,429,144, the entiretyof each of which is hereby incorporated herein by this reference). TheseWilk references teach the use of a stent which is introduced through themyocardial wall from an adjacent coronary artery to provide a bypassconduit between the left ventricle and the adjacent coronary artery. Inone embodiment, this technique teaches the delivery of a transmyocardialbypass shunt in a collapsed, reduced-profile configuration, whichrequires radial expansion subsequent to delivery in a bore preformed inthe myocardial wall. The bore is formed, for example, by a drill,needle, Seldinger wire, dilating wires or catheters, or other devicesprior to stent placement and expansion.

In another embodiment, Wilk discloses the disposition of a stent in themyocardium so that the stent extends only in the myocardium. The stentmay extend only partially through the myocardium, from the leftventricle of the heart or from a coronary artery, upstream of a vascularobstruction. Alternatively, the stent may extend completely through themyocardium to establish a blood flow path or conduit from the leftventricle to a coronary artery, downstream of a vascular obstruction.

Where stents are used in the Wilk cardiac revascularization techniquesto guide blood from the left ventricle, the stents may be designed tolock upon opening from collapsed insertion configurations. Such stentsenable the infusion of blood into the myocardium during systole. Thestents may be provided with one-way valves to regulate or control thebackflow of blood during diastole.

Thus, there is a continuing need for improved bypass methods andapparatus that allow for the realization of increased long-term patencyrates, and that are less physically traumatic to the patient.

SUMMARY OF THE INVENTION

Thus, in one preferred embodiment there is provided a new apparatus andmethod for performing a coronary artery by-pass operation which is lessinvasive and less traumatic to the patient than conventional by-passsurgery. Another advantage of this embodiment is that it requires noincision through the chest wall. In another embodiment there is provideda catheter assembly for use in performing the method of the invention.

Conduit Utilizing Intrapericardial Space

In another embodiment, there is provided methodology and related medicaldevices for effectively bypassing a blocked or partially blockedcoronary artery and providing oxygenated blood to the myocardium. Inaccordance with this embodiment, a coronary artery bypass methodutilizes a fluid communication conduit or shunt member. An upstream endportion of the shunt member is disposed in the myocardium of a patient'sheart so that the upstream end portion communicates with the leftventricle of the patient's heart. An opposite downstream end portion ofthe shunt member is placed in communication with a coronary artery ofthe patient downstream of a blockage in the coronary artery, so that anintermediate or middle portion of the shunt member is disposed in anintrapericardial space of the patient, outside of the myocardium andoutside of the coronary artery. The downstream end portion of the shuntis inserted into the coronary artery or, alternatively, attached to agenerally anterior wall of the coronary artery.

Where the downstream end portion of the shunt is attached to theanterior wall of the coronary artery, the method further comprisesforming an aperture in the anterior wall of the coronary artery afterattaching the downstream end portion of the shunt member to the anteriorwall, thereby opening communication between the shunt member and thecoronary artery. The shunt member is preferably deliveredintravascularly into the left ventricle of the patient's heart. Thedownstream end portion of the shunt member is then passed completelythrough the myocardium and the intrapericardial space to the anteriorwall of the coronary artery. The aperture in the coronary artery isformed by inserting a free end portion of an incising instrumentintravascularly and through the shunt member after disposition of theupstream end portion of the shunt member in the myocardium and afterattaching of the downstream end portion of the shunt member to thecoronary artery. The incising instrument is operated, after insertingthereof, to perforate the anterior wall of the coronary artery.

The incising instrument may be a laser instrument including an opticalfiber. The incising instrument is operated in part by transmittingmonochromatic or laser radiation through the optical fiber to theanterior wall of the coronary artery.

The method utilizing the shunt member further comprises forming apassageway through the myocardium prior to the disposing of the upstreamend portion of the shunt member in the myocardium. The passageway isformed by inserting a surgical instrument intravascularly into the leftventricle of the patient and operating the instrument from outside thepatient to bore or tunnel through the myocardium. The upstream endportion of the shunt member is disposed in the passageway andsubsequently the downstream end portion of the shunt member is placed incommunication with the coronary artery of the patient.

The shunt member may be deployed in a pericardioscopic operation whereinpericardioscopic surgical instruments are operated from outside thepatient to manipulate the downstream end portion of the shunt member andto place the downstream end portion of the shunt member intocommunication with the coronary artery of the patient after passing ofthe downstream end portion of the shunt member through the passageway inthe myocardium.

Where the downstream end portion of the shunt member is inserted intothe coronary artery, the sequence of operations is similar to the casewhere the shunt member is attached to the anterior wall of the coronaryartery. The shunt member is delivered intravascularly into the leftventricle of the patient's heart and subsequently the downstream endportion of the shunt member is passed through the myocardium; thedownstream end portion of the shunt member is then inserted into thecoronary artery. In this case, as well, the shunt member may be deployedin a pericardioscopic operation wherein pericardioscopic surgicalinstruments are operated from outside the patient to place thedownstream end portion of the shunt member in communication with thecoronary artery.

Generally, in the above-described procedure, the downstream end portionof the shunt member communicates with the coronary artery downstream ofa blockage. During systole, blood travels from the patient's leftventricle through the shunt member to the coronary artery and then tothe myocardium along natural vessels. It may be necessary, in somepatients, to provide two or more shunt members, depending on the numberof blockages and their locations along the coronary artery.

Conduit Construction

The shunt or conduit member comprises a generally tubular, rounded orcircumferential member having a length greater than a width of themyocardium. The shunt member is made of a biocompatible material such aspolyethylene or GORTEX™ and is flexible at least along the middle orintermediate portion thereof. Accordingly, the intermediate or middleportion of the shunt member may be bent into an arc to facilitate theformation of a proper junction between the downstream end portion of theshunt member and the coronary artery of the patient. The tubular shuntmember may be provided with a one-way valve preventing back flow ofblood from the coronary artery into the ventricle. In a specificembodiment of the invention, the upstream end portion of the tubularshunt member is wider than the downstream end portion.

As discussed above, an upstream end portion of a generally tubular shuntmember may be disposed in a myocardium of a patient's heart so that theupstream end portion communicates with a left ventricle of the patient'sheart, while a downstream end portion of the shunt member is insertedinto a coronary artery of the patient downstream of a blockage in thecoronary artery so that the downstream end portion is disposed insidethe coronary artery. In a variation of the present invention, the shuntmember is deployed so as to be disposed only inside the myocardium andthe coronary artery. In contrast to the above-described methodology, noportion of the shunt member lies in the intrapericardial space. In thisvariation of the method, the shunt member is again deliveredintravascularly into the left ventricle of the patient's heart, with thedownstream end portion being passed through the myocardium. However, inthis variation, the downstream end portion is inserted directly into thecoronary artery through a posterior wall thereof in contact with themyocardium.

Posterior Wall Access

A method for performing a myocardial revascularization comprises, inaccordance with another embodiment of the present invention, forming apassageway at least partially through a myocardium of a patient from anouter surface of the patient's heart, and performing a surgicaloperation at an outer end of the passageway to permanently close thepassageway at the outer end. In a particular implementation of thisembodiment of the invention, the passageway includes a portion extendingthough a posterior wall of a coronary artery and is produced by formingan aperture in an anterior wall of the coronary artery and forming thepassageway in substantial alignment with the aperture. In this case, theclosure of the passageway is effectuated particularly by closing theaperture in the anterior wall of the coronary artery. The closing of theaperture in the anterior wall of the coronary artery may be effectuatedby one or more of several techniques, including suturing, plugging, andlaser coagulation. To reinforce the closure of the artery wall, a bracemay be placed over the closure. The brace may take the form of abiocompatible patch attached to the heart via suturing or laser welding.

Conduit Configurations

Pursuant to another feature of a myocardial revascularization technique,in accordance with yet another embodiment of the present invention, astent is inserted into the passageway formed at least partially throughthe patient's myocardium. The inserting of the stent is preferablyperformed prior to the performing of the surgical operation to close thepassageway at the outer end. The myocardial revascularization technique,including the insertion of the stent, may be performed in open heartsurgery or in a pericardioscopic operation. In either case, the aperturein the anterior wall of the coronary artery and the passageway in themyocardium are formed by operating an instrument taken from the groupconsisting of a surgical drill and a surgical laser.

The passageway formed to communicate at an inner end with a leftventricle of the patient may communicate at an outer end with a coronaryartery or, alternatively, may terminate in the myocardium after closureof the outer end of the passageway. In the former case, blood flows fromthe left ventricle through the passageway, the coronary artery and bloodvessels communicating with the coronary artery. In the latter case, themyocardium is revascularized directly by the passageway, rater thanindirectly through the coronary artery and its tributaries.

In a myocardial revascularization technique in accordance with anotherembodiment of the present invention, the passageway may be one of aplurality of similarly formed passageways extending from the coronaryartery into the myocardium of the patient. Each passageway is producedby forming a plurality of openings in the anterior wall of the coronaryartery and forming the passageways in alignment with respective ones ofthe openings. The passageways are effectively closed from the externalenvironment (the intrapericardial space) by closing the openings in theanterior wall of the coronary artery. Where a myocardial passagewayformed in accordance with this embodiment does not extend through orinto a coronary artery, the closure of the passageway is effectuated onan epicardium of the patient.

A stent for a coronary artery bypass or myocardium revascularizationprocedure in accordance with another embodiment of the present inventionhas a collapsed configuration and an expanded configuration. Theexpanded configuration may have an arcuate form, to provide a curvedflow path for blood upon implantation of the stent into a myocardium ofa patient. This curved flow path smoothly redirects blood flow andminimizes possible adverse effects that the impulsive force of the bloodmight have on the patient's coronary artery and other layers of hearttissue. The stent may have a one-way valve for preventing retrogradeflow of blood.

Another stent in accordance with another embodiment has a collapsedconfiguration and an expanded configuration and is provided with asensor and means for transmitting signals from the sensor to a receiverexternal to the stent. The sensor is taken from the group consisting ofa pressure sensor and a flow sensor.

Self-Inserting Conduits

In yet another embodiment of the present bypass apparatus there isprovided a self-inserting conduit for diverting blood directly from theleft ventricle of the heart to the coronary artery at a point distal tothe blockage, therefore bypassing the blocked portion of the vessel. Theshunt comprises a stent in the form of a single conduit having anopening at either end, and adapted to be positioned in the myocardium.The coronary artery, the myocardium and the wall of the left ventricleof the heart are pierced by the conduit from an outside space or tissuein a transverse manner to provide a channel completely through from thecoronary artery to the left ventricle of the heart. An opening locatedon the distal end of the conduit is positioned in the coronary artery.Oxygenated blood is pumped from the left ventricle, through the distalopening, through the hollow central portion of the conduit, out of theproximal opening and into the coronary artery distal to the blockage.The conduit is anchored in the myocardium to provide a permanent passagefor blood to flow between the left ventricle of the heart and thecoronary artery, distal to the blockage.

The apparatus of the present invention is preferably implanted in aminimally invasive manner using thoroscopy or another endoscopicprocedure, although open surgery or other means of vascular access arealso possible.

Coronary Bypass

The present system preferably utilizes a combination conduit comprisingan access and shunt device for forming a diversion of the blood from thecoronary and proximally to the stenosis. A similar access and shuntdevice is located in the vessel distal of the stenosis to receive thediverted blood and allow it to continue on its course downstream. Thecombination access/shunt device comprises a conduit element forproviding access to the vessel and anchoring the system in place. Theconduit pierces the artery from the outside and travels completelythrough it and into the myocardium or other heart tissue adjacent thecoronary artery. The conduit has a conduit or barb or series of barbs onits distal end and is otherwise designed so that it has substantialresistance to pull back or exit from the vessel. As noted, the conduitpierces through the vessel from an outside space or tissue in atransverse manner. Mounted on top of the conduit is a shunt device whichcomprises an aperture and a diversion conduit. With the conduit in itsanchoring position, the shunt device is located partially in the vesseland partially outside of the vessel from the direction in which theconduit entered. The aperture resides in the vessel to allow blood toenter therein and from there to the diversion tube which is in fluidcommunication with the aperture. This provides the shunt of blood intothe diversion tube of the combination access/shunt device. Mounted ontop of the diversion tube is a connector piece which mates with a bypassconduit. These elements are also in fluid communication to allow theblood to bypass the blockage and to be shunted to a location distalthereof.

At such distal location, another similar combination access/shunt deviceis placed to allow the shunted blood to re-enter the artery in afree-graft configuration, and continue on its path downstream. However,a single device can be used distal of the restriction and connected toan appropriate graft for revascularization.

The apparatus of the present invention is preferably implanted in aminimally invasive manner using thoroscopy or other endoscopicprocedure, although open surgery or other means of vascular access arealso possible. The apparatus can be implanted permanently, or can beused temporarily to provide a bypass system during various surgicalprocedures, including coronary bypass procedures.

Thus, the present system is used to direct the flow of blood around theblocked portion of the vessel. In one embodiment, a shunt is used todirect blood directly from the left ventricle of the heart to thecoronary artery at a point distal to the blockage. According to oneaspect of the invention, the shunt comprises a rigid, generallyelongated stent in the form of a single conduit having an opening ateither end, and adapted to be positioned in the myocardium. The coronaryartery, the myocardium and the wall of the left ventricle of the heartare pierced by the conduit from an outside space or tissue in atransverse manner to provide a channel completely through from thecoronary artery to the left ventricle of the heart. An opening locatedon the distal end of the conduit is positioned within the leftventricle. An opening on the proximal end of the conduit is positionedin the coronary artery. Oxygenated blood is pumped from the leftventricle, through the distal opening, through the hollow centralportion of the conduit, out of the proximal opening and into thecoronary artery distal to the blockage. The conduit is anchored in themyocardium to provide a permanent passage for blood to flow between theleft ventricle of the heart and the coronary artery, distal to theblockage.

Alternatively, the conduit can be used temporarily to maintain bloodflow through the coronary artery during therapeutic procedures, such ascoronary bypass. The conduit can be used to deliver a vein graft, and toprovide for the passage of blood around the blockage until theanastomosis of the graft is complete.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A–1E are schematic cross-sectional views of a human heart,showing successive steps in a transmyocardial coronary artery bypassoperation in accordance with one conduit embodiment of the presentinvention.

FIG. 2 is a schematic cross-sectional view of a human heart showing analternative conduit to that used in the operation of FIGS. 1A–1E.

FIG. 3 is a schematic partial cross-sectional view, on a larger scale,showing a modification of the coronary artery bypass produced by theoperation of FIGS. 1A–1E.

FIG. 4 is a schematic cross-sectional view of a human heart showing amodification of the coronary artery bypass operation depicted in FIGS.1A–1E.

FIG. 5 is a schematic partial cross-sectional view, on a larger scale,showing a variation of the coronary artery bypass of FIG. 4.

FIG. 5A is a schematic view of a human heart showing a two piece conduitconnecting the left ventricle to the left anterior descending coronaryartery.

FIG. 5B is an enlarged view of the two piece conduit of FIG. 5A.

FIG. 5C is a schematic cross-sectional view of the two piece conduit ofFIG. 5B.

FIG. 6A is a schematic partial cross-sectional view of another coronaryartery bypass showing a conduit or shunt with a one-way valve openedduring systole.

FIG. 6B is a schematic partial cross-sectional view similar to FIG. 6A,illustrating the shunt of FIG. 6A with the valve closed during diastole.

FIGS. 6C–6H are perspective views of conduits or stents with openingsinto the coronary artery having hoods, valves, or other flowdirection/flow control devices.

FIG. 7 is a schematic cross-sectional view of a human heart showinginstrumentation used for implanting the shunt of FIGS. 6A and 6B.

FIG. 8 is a schematic partial cross-sectional view of an arcuate conduitor stent with a one-way valve utilized in a further coronary arterytechnique.

FIGS. 8A–8B are schematic partial cross-sectional views of arcuateconduits or stents having narrow openings into the coronary artery.

FIGS. 8C–8P are schematic partial cross-sectional views of conduits orstents having a variety of configurations to achieve flow controltherethrough and to minimize backflow.

FIG. 9 is a block diagram of operational components with feedback as tooperational parameters.

FIGS. 9A–9B illustrate a conduit having a flow sensor for measuringvarious blood flow parameters incorporated therein.

FIG. 9C is a schematic partial cross-sectional view of a conduit havingthe flow sensor FIG. 9B as installed between two vessels.

FIGS. 10A–10C are schematic cross-sectional views of a human heart,showing successive steps in a transmyocardial coronary artery bypassoperation utilizing a penetrating rod for implanting a conduit.

FIG. 11 is a schematic cross-sectional view similar to FIG. 10C, showingthree transmyocardial conduits or stents implanted pursuant to theprocedure of FIGS. 10A–10C.

FIG. 12 is a schematic partial cross-sectional view of an artificialmyocardial revascularization showing a plurality of partial conduits orstents extending from a coronary artery partially into the myocardium.

FIG. 13 is a schematic front elevational view of a human heart, showingan improvement in the myocardial revascularization of FIG. 12.

FIGS. 14A and 14B are schematic cross-sectional views of a human heart,showing successive steps in an artificial myocardial revascularizationprocedure, resulting in a plurality of conduits or stents extending froma left ventricle of the heart at least partially into the myocardium.

FIG. 15 is a schematic partial cross-sectional view of a human heart,illustrating a modification to the artificial myocardialrevascularization of FIG. 14B.

FIG. 16 is a schematic partial cross-sectional view of a human heart,illustrating a heart provided in a left ventricle with implants orplugs.

FIG. 16A is a schematic partial cross-sectional view of a conduit orplug, having therapeutic materials applied thereto.

FIG. 16B is a side view of a biodegradable conduit or stent positionedwithin the myocardium, with the coronary artery and myocardium showncut-away.

FIGS. 16C–16F are schematic, cross-sectional views of the externalinsertion of an absorbable intramyocardial plug in the myocardium.

FIGS. 16G–16I are schematic, cross-sectional views of the insertion ofabsorbable intramyocardial plugs in the myocardium via the leftventricle.

FIGS. 16J–16N are schematic, cross-sectional views of the externalinsertion of absorbable intramyocardial plugs used to form a conduit orshunt through the myocardium from the left ventricle to the coronaryartery.

FIGS. 16O–16S are schematic, cross-sectional views of the externalinsertion of absorbable intramyocardial plugs in the myocardium.

FIG. 17 is a small scale cross-sectional view of a heart with a blockagein the coronary artery and illustrating a self-inserting conduit.

FIG. 18 is a close-up perspective view of one embodiment of the deviceof FIG. 17 shown implanted in the myocardium, with the coronary artery,myocardium and left ventricle of the heart shown cut-away.

FIG. 18A is a schematic partial cross-sectional view of a self-insertingconduit, having dual prongs in the head or flange thereof to preventrotation.

FIGS. 19A–C illustrate a method for implanting the conduit device ofFIG. 17.

FIGS. 20A–B illustrate an alternate method for implanting the conduitdevice of FIG. 17.

FIG. 21 is a small scale cross-sectional view of a heart with a blockagein the coronary artery, and further illustrating another embodiment ofthe bypass device of this embodiment;

FIG. 22 is a close-up cross-sectional view of the blockage in thecoronary artery and illustrating in greater detail the bypass device ofthe present invention;

FIGS. 22A–22B are schematic partial cross-sectional views of conduitssimilar to that described in FIG. 22 illustrating alternative blood flowembodiments.

FIG. 23 is a perspective view of the bypass device and conduit;

FIG. 24 is a close-up view of a combination access/shunt conduit devicehaving a distal tip;

FIG. 25 is a perspective view of an alternative embodiment of acombination access/shunt device conduit;

[FIG. 26 is reserved]

FIG. 27 is a perspective view of a third combination access/shuntembodiment which has a tapered configuration;

FIG. 28 is a perspective view of a fourth combination access/shuntembodiment with dual distal tips.

FIG. 29 is a perspective view of a conduit or shunt device according toa fifth embodiment of a combination access/shunt;

FIG. 30 is a perspective view of a conduit or shunt device according toa sixth embodiment of a combination access/shunt;

FIG. 31 shows the shunt device of FIG. 29 in cross-section;

FIG. 32 is a close-up cross-sectional view of a coronary artery blockageand the myocardium of a patient and the shunt device according to FIG.29;

FIG. 33 is a perspective view of a side-by-side bypass device;

FIG. 33A is a schematic cross-sectional view illustrating the coronarybypass system which is more parallel to the coronary artery.

FIG. 34 is a perspective view of another side-by-side bypass embodiment;

FIG. 35 is a perspective view of a third side-by-side bypass embodiment;

[FIG. 36 is reserved]

FIG. 37 is a close-up cross-sectional view of a coronary artery and themyocardium of a patient and the shunt device according to FIG. 34;

FIG. 38 is a close-up cross-sectional view of a coronary artery of apatient and the shunt device according to FIG. 36.

FIGS. 39A–B illustrate the temporary use of a stent during a coronarybypass procedure.

FIGS. 40 and 40A–40Q show a variety of members for securing segments oftissue to each other, as well as conduit members.

FIG. 41 shows a conduit of variable wall thickness.

FIGS. 41A–41G show a variety of cross-sectional views of a conduithaving varying wall thicknesses.

FIGS. 42, 43, 44A–44C, and 45 show conduits designed to take advantageof flow resistance to facilitate flow control.

FIGS. 46, 47A–47D, 48, 48A–48C, and 49 show curved conduits that directblood flow downstream in a direction that is substantially parallel tothe bloodstream in the vessel.

FIGS. 50A–50C and 51A–51D show a variety of conduits of a latticeconstruction.

FIG. 52 shows a conduit having a T-like distal portion.

FIG. 53 shows a conduit that has an articulating distal portion.

FIG. 54 shows a conduit that has an elastomeric distal anchoring arm.

In the drawings, the same reference designations are used to designatethe same objects. The word “distal” when used herein designates aninstrument end which is spaced from the surgeon, radiologist or otheroperator. The physical relation of the instrument to the patient is notdeterminative.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The principles of the present invention are not limited to leftventricular conduits, and apply to conduits for communicating bodilyfluids from any space within a patient to another space within apatient, including any mammal. Furthermore, such fluid communicationthrough the conduits is not limited to any particular direction of flowand can be antegrade or retrograde with respect to the normal flow offluid. Moreover, the conduits may communicate between a bodily space anda vessel or from one vessel to another vessel (such as an artery to avein or vice versa). Moreover, the conduits can reside in a singlebodily space so as to communicate fluids from one portion of the spaceto another. For example, the conduits can be used to achieve a bypasswithin a single vessel, such as communicating blood from a proximalportion of an occluded coronary artery to a more distal portion of thatsame coronary artery.

In addition, the conduits and related methods can preferably traversevarious intermediate destinations and are not limited to any particularflow sequence. For example, in one preferred embodiment of the presentinvention, the conduit communicates from the left ventricle, through themyocardium, into the intrapericardial space, and then into the coronaryartery. However, other preferred embodiments are disclosed, includingdirect transmyocardial communication from a left ventricle, through themyocardium and into the coronary artery. Thus, as emphasized above, theterm “transmyocardial” should not be narrowly construed in connectionwith the preferred fluid communication conduits, and othernon-myocardial and even non-cardiac fluid communication are preferred aswell. With respect to the walls of the heart (and more specifically theterm “heart wall”), the preferred conduits and related methods arecapable of fluid communication through all such walls including, withoutlimitation, the pericardium, epicardium, myocardium, endocardium,septum, etc.

The bypass which is achieved with certain preferred embodiments andrelated methods is not limited to a complete bypass of bodily fluidflow, but can also include a partial bypass which advantageouslysupplements the normal bodily blood flow. Moreover, the occlusions whichare bypassed may be of a partial or complete nature, and therefore theterminology “bypass” or “occlusion” should not be construed to belimited to a complete bypass or a complete occlusion but can includepartial bypass and partial occlusion as described.

The preferred conduits and related methods disclosed herein can alsoprovide complete passages or partial passages through bodily tissues. Inthis regard, the conduits can comprise stents, shunts, or the like, andtherefore provide a passageway or opening for bodily fluid such asblood. Moreover, the conduits are not necessarily stented or lined witha device but can comprise mere tunnels or openings formed in the tissuesof the patient.

The conduits of the present invention preferably comprise both integralor one-piece conduits as well as plural sections joined together to forma continuous conduit. In this regard, the anastomotic devices andmethods utilized in connection with the various embodiments of thepresent invention are to be broadly construed to relate to connectionsof these various components. The present conduits can be deployed in avariety of methods consistent with sound medical practice includingvascular or surgical deliveries, including minimally invasivetechniques. For example, various preferred embodiments of delivery rodsand associated methods are disclosed. In one embodiment, the deliveryrod is solid and trocar like. It may be rigid or semi-rigid and capableof penetrating the tissues of the patient and thereby form the conduit,in whole or in part, for purposes of fluid communication. The deliveryrod may be an incising instrument such as a laser or a drill. In otherpreferred embodiments, the delivery rods may be hollow so as to form theconduits themselves (e.g., the conduits are preferably self-implantingor self-inserting) or have a conduit mounted thereon (e.g., the deliveryrod is preferably removed leaving the conduit installed). Thus, thepreferred conduit device and method for installation is preferablydetermined by appropriate patient indications in accordance with soundmedical practices.

Further details regarding conduits and conduit delivery systems aredescribed in U.S. patent application Ser. No. 09/368,868, filed Aug. 4,1999, now U.S. Pat. No. 6,261,304, entitled DELIVERY METHODS FOR LEFTVENTRICULAR CONDUIT, U.S. application Ser. No. 09/369,048 filed Aug. 4,1999, now U.S. Pat. No. 6,290,728, entitled DESIGNS FOR LEFT VENTRICULARCONDUIT, U.S. application Ser. No. 09/369,061, filed Aug. 4, 1999, nowU.S. Pat. No. 6,254,564, entitled LEFT VENTRICULAR CONDUIT WITH BLOODVESSEL GRAFT, U.S. application Ser. No. 09/368,393, filed Aug. 4, 1999,now pending, entitled VALVE DESIGNS FOR LEFT VENTRICULAR CONDUIT, andU.S. application Ser. No. 09/368,644, filed Aug. 4, 1999, now U.S. Pat.No. 6,302,892, entitled BLOOD FLOW CONDUIT DELIVERY SYSTEM AND METHOD OFUSE and U.S. Pat. Nos. 5,429,144 and 5,662,124, the disclosures of whichare all hereby incorporated by reference in their entirety.

Conduits Utilizing Intrapericardial Space

In a transmyocardial coronary artery bypass operation illustrated inFIGS. 1A–1E, a catheter 12 is inserted over a guidewire (notillustrated) through the vasculature of a patient and particularlythrough the aorta AO into the left ventricle LV of the patient's heartPH. (Although the embodiments described herein are discussed withrespect to the left ventricle LV, they may also be applied to the rightventricle RV and the right and left atria.) Upon arrival of a distal endof catheter 12 in left ventricle LV, the guidewire is withdrawn and asurgical incising instrument 14 such as a light-transmitting opticalfiber is inserted through catheter 12. The catheterization procedure ismonitored via conventional radiographic techniques or, alternatively,via a CAT scanner or MRI machine.

Upon ejection of a distal tip of optical fiber 14 from catheter 12 intoleft ventricle LV, the fiber tip is placed into contact with a heartwall HW of the patient at a predetermined location downstream of anarterial blockage BL in the coronary artery CA of the patient, asillustrated in FIG. 1A. A laser source 16 is then activated to transmitmonochromatic electromagnetic radiation along optical fiber 14 to heartwall HW. The distal end of fiber 14 is pushed through heart wall HW,with the radiation being continuously or periodically transmittedthrough optical fiber 14, thereby forming a transmyocardial passageway18 in heart wall HW (FIG. 1B).

After the formation of passageway 18, optical fiber 14 is withdrawn fromcatheter 12 and replaced with a guidewire 20 (FIG. 1C). In addition,catheter 12 is pushed in a forward direction through passageway 18 sothat a distal end portion of the catheter extends outwardly frompassageway 18 into an intrapericardial space IS. A shunt 22 made offlexible biocompatible material such as polyethylene or GORTEX™ is thenpassed over guidewire 20 and through catheter 12. At this juncture, aforceps instrument 24 (FIGS. 1C and 1D) inserted into the patient via apericardioscopic cannula or port (not shown) or through an open incision(not shown) is used to grasp shunt 22 and direct a free end of the shuntto an anterior wall AW of coronary artery CA, as illustrated in FIG. 1D.A laser instrument 26 is then used to attach the free end of shunt 22 tothe anterior wall AW of coronary artery CA. At this point in theoperation, there is no avenue of communication between left ventricle LVand coronary artery CA.

After the attachment of shunt 22 to anterior wall AW of coronary arteryCA, optical fiber 14 is again inserted through catheter 12 and throughshunt 22 to anterior wall AW of coronary artery CA. Laser source 16 istemporarily activated to form an aperture in anterior wall AW ofcoronary artery CA inside shunt 22, thereby establishing atransmyocardial coronary artery bypass path from left ventricle LV intothe coronary artery downstream of blockage BL as illustrated in FIG. 1E.After the formation of the aperture in coronary artery CA, fiber 14 iswithdrawn from shunt 22 and catheter 12 is withdrawn from heart wall HW.Optical fiber 14 may be used at that time (or previously) to attach anupstream end of shunt 22 to heart wall HW at left ventricle LV. Theoptical fiber 14 and catheter 12 are then extracted from the patient.The deployed shunt 22 extends from left ventricle LV through heart wallor myocardium HW to anterior wall AW of coronary artery CA, with amiddle or intermediate portion (not separately designated) of shunt 22being disposed in intrapericardial space IS.

FIG. 2 depicts a transmyocardial coronary artery bypass similar to thatshown in FIG. 1E, except that a different shunt 28 is used. Shunt 28 isprovided at opposite ends with flanges 30 and 32 in the form of annulardisks. These flanges 30 and 32 facilitate the attachment of shunt 28 tothe heart wall HW at left ventricle LV and to anterior wall AW ofcoronary artery CA, respectively. The attachment of flanges 30 and 32 toheart wall HW and coronary artery CA may be effectuated by laserinstrument 26 and/or by other techniques including gluing and suturing.Shunt 28 is installed in the manner described above with reference toFIGS. 1A–1E.

The structure of shunt 28, as well as different uses thereof, isdescribed and illustrated in U.S. Pat. No. 5,470,320, the disclosure ofwhich is hereby incorporated by reference.

FIG. 3 shows a modification of the transmyocardial coronary arterybypass of FIG. 1E. The downstream end of shunt 22 is attached toanterior wall AW of coronary artery CA via sutures 34. A stent 36 with aone-way valve 38 is placed inside an upstream portion of shunt 22located within heart wall or myocardium HW. Stent 36 functions to clampthe upstream end of shunt 22 to heart wall HW. One-way valve 38 permitsblood to flow from ventricle LV to coronary artery CA during systole andprevents backflow to ventricle LV during diastole. Where shunt 22 isinstalled without stent 36, shunt 22 may be provided with an integralone-way valve (not illustrated). Stent 36 is generally introduced intoheart PH in a collapsed configuration through a catheter. Stent 36 maybe predisposed inside the upstream end portion of shunt 22 and insertedtherewith into heart PH. Alternatively, stent 36 may be inserted intoshunt 22 after the shunt has been passed through passageway 18 andbefore or after the attachment of the downstream end of shunt 22 toanterior wall AW of coronary artery CA. Stent 36, and other stents andshunts disclosed herein, may be provided with outwardly projecting barbs(not illustrated) for anchoring the stent or shunt to the myocardium.

In another variation (not illustrated) of the transmyocardial coronaryartery bypass of FIG. 1E, shunt 22 has an upstream portion which is astent. The stent is substantially coextensive with or smaller thanpassageway 18 and is accordingly lodged completely within passageway 18upon installation of the shunt 22. The remainder of the shunt 22 is madeof a continuous, essentially impermeable biocompatible film material, asin the embodiment discussed above.

As illustrated in FIG. 4, another modification of the transmyocardialcoronary artery bypass of FIG. 1E includes the insertion of a downstreamend portion 40 of shunt 22 through an aperture 42 formed in anteriorwall AW of coronary artery CA downstream of blockage BL. Clearly, inthis bypass procedure, aperture 42 is formed in coronary artery CA priorto the joining of the downstream end portion 40 of shunt 22 and coronaryartery CA. Aperture 42 is formed by an incising instrument (not shown)such as a laser or a scalpel blade which is inserted intointrapericardial space IS either through a pericardioscopic cannula orport (not shown) or through an open incision. Shunt 22 may be attached,by laser welding, glue or sutures, to coronary artery CA at aperture 42.As discussed hereinabove with respect to the embodiment of FIG. 1E, anintermediate or middle portion 44 of shunt 22 is disposed insideintrapericardial space IS upon deployment of shunt 22. A brace 48, forexample, in the form of a patch (compare with FIG. 13), may be disposedover middle portion 44 of shunt 22 and attached to heart PH, to supportthe shunt 22 against possible dislodgment owing to the hydraulic forcesof blood flow and the mechanical forces of myocardium contraction. Braceor patch 48, and similar braces or patches disclosed herein, is made ofa strong biocompatible material such as KEVLAR™,polytetrafluoroethylene, silicone, etc.

FIG. 5 illustrates the shunt-implemented transmyocardial coronary arterybypass of FIG. 4, with a one-way valve 50 being provided at the upstreamend of shunt 22 for permitting blood flow from ventricle LV intocoronary artery CA during systole and for preventing blood flow fromcoronary artery CA toward ventricle LV during diastole.

Conduit Configurations

FIG. 5A illustrates a human heart PH, showing more particularly the leftanterior descending coronary artery CA. The technical challengepresented herein is placing a conduit accurately and aligned properlybetween the left ventricle LV and the coronary artery CA. A conduit 49is shown in FIGS. 5A–5C comprising two separate pieces, namely an accessport 51 which punctures through the heart wall HW, including themyocardium, to the left ventricle LV, and an anastomosed segment 53. Toplace the conduit 49, the access port 51 is inserted into the heart wallHW from the outside of the heart PH, preferably adjacent but notnecessarily through the coronary artery CA. Flange 55 determines theposition of the port 51 by pressing against the outside of the heart PH,and the port extends into the left ventricle LV with a lumen 57extending therethrough. The end of the port 51 on the outside of theheart wall HW may be curved as shown in FIG. 5C. After the port 51 isinserted, the port is connected to the artery CA preferably using asegment 53 which is more preferably an artificial graft. The locationwhere the segment 53 is anastomosed to the coronary artery maypreferably be downstream of a blockage (not shown) in the coronaryartery CA.

The embodiment of FIGS. 5A–5C is advantageous in that it does notrequire extremely accurate placement of the port 51 into the heart PH.This is especially important because during a beating heart procedureplacement of a device through the heart PH may be difficult. Morespecifically, as shown in FIGS. 5A–5C, the port 541 need not bepositioned at a very precise position through or adjacent the coronaryartery CA. Rather, the port 51 need only be placed near the coronaryartery CA, and the graft segment 53 is used to connect the port 51 tothe coronary artery CA. It will be appreciated that multiple conduitsmay be made to the artery CA.

As depicted in FIGS. 6A and 6B, a transmyocardial coronary artery bypassis implemented by a conduit or shunt member 52 provided at an upstreamend with a one-way valve 54. Shunt member 52 extends directly from leftventricle LV through heart wall HW into coronary artery CA and includesan upstream portion 56 disposed within heart wall or myocardium HW and adownstream portion 58 disposed in coronary artery CA. Shunt member 52may have a tapered form which narrows down in a downstream direction sothat downstream portion 58 is of smaller cross-section than upstreamportion 56. Upstream portion 56 may take the form of a stent which isexpanded from a collapsed insertion configuration to an expanded useconfiguration to lock or clamp shunt member 52 to a passageway 60 formedin heart wall or myocardium HW prior to the insertion of shunt member52. Downstream portion 58 is made of a continuous, essentiallyimpermeable biocompatible film material. In addition, upstream portion56 may be flexible to an extent so as to expand, if necessary, duringdiastole (FIG. 6B) to accommodate some backflow. It will also be notedin connection with FIG. 6B, the upstream portion 56 also acts as areservoir to accumulate blood during systole which is then passed intothe coronary artery CA during diastole.

Shunt 52 is curved and bears the force of the blood ejected from leftventricle LV through passageway or channel 60 during systole.

Other one way valve embodiments are shown in FIGS. 6C–6H and areparticularly useful for directing laminar flow and controlling the flowof blood. FIGS. 6C and 6D show the open and closed positions,respectively, of a conduit 700. The conduit comprises a relatively soft,pliable portion 704 and a harder, firmer portion 708. In the openconfiguration (FIG. 6C), blood flows out of a hole 712 in the conduit700 and into the left ventricle LV. The softer portion 704 has aresiliency such that a hood or flap portion 716 closes during diastole,thereby blocking the flow of blood.

FIGS. 6E and 6F show another one way valve conduit embodiment 720 thatcomprises soft and hard portions 724 and 728, respectively. The softportion 724 includes a flap portion 732 having a series of slits 736therein which may be spaced equidistantly from each other as shown, oralternatively, the slits may be spaced unequally from each other. Theresiliency of the conduit 720 is such that it is open during systole(FIG. 6F) but closes partially during diastole (FIG. 6F).

FIGS. 6G and 6H show another one way valve conduit embodiment 740comprising soft and hard portions 744 and 748, in which a single slit752 is formed in the soft portion 744. As in embodiments 6C–6D and6E–6F, the resiliency of the soft portion is such that the conduit 740acts as a one-way valve, with the conduit opening during systole andpartially closing during diastole. Further, conduits (not shown) havingan opening for blood flow, but no slits, may be used in which theportion of the conduit around the opening partially or completelycollapses (closes) during diastole, but is at least partially openduring systole.

As illustrated in FIG. 7, the deployment or installation of shunt 52 inan intravascular procedure requires instrumentation for enabling theprecise locating of the coronary artery CA with respect to possibleinsertion points in left ventricle LV. To that end, a first catheter 62is utilized which is provided at a distal end with an electroacoustictransducer (not illustrated) for converting an electrical signal ofultrasonic frequency to a mechanical pressure wave which is transmittedthrough a posterior wall PW of coronary artery CA and heart wall ormyocardium HW. Catheter 62 and particularly the electroacoustictransducer (not shown) is operatively connected to an ultrasonic wavegenerator 64. Another catheter 66 is also inserted through aorta AO (andover a conventional guidewire, not illustrated). This second catheter 66is introduced into left ventricle LV and is provided at a free end withan acoustoelectric transducer (not shown) for detecting pressure wavesin an ultrasonic frequency range. Catheter 66 and its acoustoelectrictransducer are operatively connected to an ultrasonic wave analyzer 68which calculates the location of the distal tip of catheter 62 relativeto the distal tip of catheter 66 and thus provides feedback to a surgeonor an insertion device for determining an insertion point and insertionangle for surgical incising instrument such as optical fiber 14 (FIG.1A).

Several shunt members 22 or 52 may be necessary in cases of multiplecoronary artery blockages. These multiple shunt members each tap intothe coronary artery at a point downstream of a respective blockage.

As depicted in FIG. 8, a transmyocardial stent 70 for maintaining acirculation path between left ventricle LV of patient's heart PH andcoronary artery CA is curved in the longitudinal or flow direction toprovide an arcuate flow path. This curvature serves to deflect thehydraulic forces from a direction substantially perpendicular tocoronary artery CA to a direction substantially parallel to coronaryartery CA. This deflection serves to prevent coronary artery dilatationand to protect anterior wall AW of artery CA from the substantialhydraulic forces generated during systole. Thus, this deflection servesto control the flow of the blood through the stent 70 during systole.Moreover, since the stent 70 narrows and curves towards the coronaryartery CA, it serves to prevent or minimize backflow into the stent 70during diastole, thus obviating the need for a valve 72. Stent 70 may beoptionally provided with a one-way valve 72 and may be deployed asdiscussed above with reference to FIG. 7. Curved stent 70 may be used asupstream portion 56 of shunt member 52 or in place of stent 36 (FIG. 3)or as an upstream portion of shunt 22. FIGS. 8A and 8B illustratefurther arcuate stent embodiments for maintaining circulation betweenthe left ventricle LV and the coronary artery CA. As in FIG. 8, theembodiments of FIGS. 8A and 8B include a transmyocardial stent 70 thatis curved in the longitudinal or flow direction to provide an arcuateflow path.

FIGS. 8C and 8D illustrate how a catheter 800 may be introduced into thecoronary artery CA (FIG. 8C) or on both sides of the heart wall (FIG.8D) for boring out a portion of the heart wall HW to form anhourglass-shaped portion 804 within the heart wall HW. The hourglassshaped portion 804 acts to create a valve effect so that blood is atleast partially blocked during diastole.

As seen in FIGS. 8E and 8F, a stent 808 may be positioned within theheart wall HW. As shown in FIG. 8E, the stent 808 is driven towards aclosed position during diastole, whereas FIG. 8F shows the open positionof the stent during systole. FIGS. 8G and 8H show an embodimentanalogous to FIGS. 8E–F, except that a stent 812 is used that has avarying thickness. Using a stent 812 of nonconstant thickness has theeffect of accentuating the deflection of the stent 812 at its centralportion 814 relative to that at the outer portions 816 of the stent (atits ends).

Other stent designs may be used like the parallelpiped shaped stents 818of FIGS. 8L–M (which may include a movable flap portion 820 forcontrolling the flow of blood) or the stents 824 illustrated in FIGS.8N–O (which likewise may include a movable flap 828 for controlling theflow). FIGS. 8–8K show another embodiment which includes aconically-shaped stent 832 whose base is located on the coronary arteryside. The stent 832 includes rims 834 and 836 for securing the stent 832to the heart wall HW.

FIG. 8P illustrates an embodiment of a stent 850 which, like theembodiment of FIG. 8, maintains a circulation path between the leftventricle LV of patient's heart PH and coronary artery CA. The stent 850has a lumen 852 therein which is curved, thereby deflecting hydraulicforces to control the flow of the blood through the stent 850 duringsystole. Further, the lumen 852 narrows and curves towards the coronaryartery CA, which reduces backflow into the stent 850 during diastole andreduces the need for a valve. Nevertheless, the stent 850 may beoptionally provided with a one-way valve 72 and may be deployed asdiscussed above with reference to FIG. 7. Further, the stent 850 may beused as upstream portion 56 of shunt member 52 or in place of stent 36(FIG. 3) or as an upstream portion of shunt 22. Unlike its counterpartin FIG. 8, however, the lumen 852 of FIG. 8P is oriented within thestent 850 such that the lumen 852 joins the coronary artery CA at anoblique angle when the stent 850 is oriented perpendicular to thecoronary artery CA. This aids the practitioner in the proper positioningof the lumen 852, and insures that the lumen 852 will be oriented withrespect to the coronary artery CA as shown in FIG. 8P when a flange 854of the stent 850 is positioned against the coronary artery CA. Further,the stent 850 of FIG. 8P may advantageously have an outer dimension thatis substantially constant in cross section.

A shunt or stent 74 may be provided with a pressure sensor 76 and/or aflow sensor 78, as illustrated in FIG. 9. Sensors 76 and 78 are attachedto or incorporated into a wall 80 of shunt or stent 74 and have outputsoperatively connected to a transmitter 82 which is also attached to orincorporated into shunt or stent wall 80. Output signals from sensors 76and 78 which encode data pertaining to pressures and flow rates arerelayed to a receiver 84 via transmitter 82. Transmitter 82 may bewireless or connected by a wire 86 to receiver 84. The pressure and flowrate data collected via sensors 76 and 78 are useful for monitoring theeffectiveness of the implanted stents or shunts for any particularpatient and thereby determining whether additional stents or shunts maybe necessary for that patient. Receiver 84 may be physically located ona chest of the patient or otherwise nearby.

FIG. 9A illustrates a cross-section of the heart illustrating a stent900 having incorporated therein a sensor 904 (shown in FIG. 9B) similarto the sensors described above in connection with FIG. 9. The sensor maybe incorporated into the wall of the stent 900 as illustrated in FIG. 9Bor may be associated with a stent in some other fashion. The sensor 904may advantageously transmit an output signal which encodes data withrespect to pressures and flow rates. For example, blood pressure duringboth systole and diastole may be monitored, and the sensor 904 may beused to indicate when the blood flow (or pressure) is decreasing or whenthe blood flow (or pressure) falls beneath a certain level. As shown inFIG. 9C, a conduit 910 having a sensor therein may be used between twovessels, such as an aorta 912 and a vein 914.

Posterior Wall Access

As illustrated in FIGS. 10A–10C, a transmyocardial coronary arterybypass may be performed from outside the patient's vascular system. Anincising instrument 88 such as a laser or a drill is insertedpericardioscopically or through an open incision into theintrapericardial space IS and is operated to bore a passageway 90 in theheart wall or myocardium HW via the coronary artery CA, as shown in FIG.10A. Passageway 90 (FIG. 10B) extends through heart wall HW andposterior wall PW of coronary artery CA and is aligned with an aperture92 formed in anterior wall AW of coronary artery CA by the incisinginstrument 88.

Upon the formation of passageway 90, a stent 94 (FIG. 10C) is insertedin a collapsed configuration into the passageway and then expanded.Stent 94 may be inserted from outside the patient's vascular system,either through an open incision in the patient's chest or through apericardioscopic cannula or port. Alternatively, stent 94 may be placedvia a catheter 96 inserted through the vascular system including theaorta AO and the left ventricle LV. As in all cases of stentimplantation described herein, stent 94 serves to maintain passageway 90in an open state, i.e., prevents the closure of passageway 90 bymuscular contraction forces during systole and, in the longer term, bynatural healing processes of the myocardium.

After the formation of passageway 90 and after the installation of stent94 via an extravascular operation, aperture 92 is closed, via sutures(not shown) and/or via a plug 98 (FIG. 10C) or patch which is stitchedor laser bonded to anterior wall AW of coronary artery CA. If stent 94is placed via an intravascular operation, aperture 92 is preferablyclosed prior to the disposition of the stent inside passageway 90. Abrace 100 in the form of a patch is optionally placed over plug 98 andfastened to heart PH via sutures, glue or welding to support the plugagainst possible dislodgment under blood pressure forces.

FIG. 11 illustrates a triple transmyocardial coronary artery bypasswherein a plurality of stents 94, 94 a and 94 b are placed in respectivepassageways (not separately designated) extending through heart wall ormyocardium HW and posterior wall PW of coronary artery CA. Thepassageways are formed and the stents 94, 94 a and 94 b inserted asdescribed hereinabove with reference to FIGS. 10A–10C. Plugs 98, 98 aand 98 b are positioned in respective apertures (not separatelydesignated) which are formed, as discussed above, in alignment with thepassageways of stents 94, 94 a and 94 b. A brace 102 in the form of apatch is optionally placed over plugs 98, 98 a and 98 b and fastened toheart PH via sutures, glue or laser welding.

FIG. 12 depicts a modification of the transmyocardial coronary arterybypass of FIG. 11, wherein passageways 104 a, 104 b, 104 c and 104 d areformed by the extravascular technique discussed above with reference toFIGS. 10A–10C but which extend through posterior coronary artery wall PWand only part of the heart wall or myocardium HW from coronary arteryCA. Stents 106 a, 106 b, 106 c and 106 d are inserted into respectivepassageways 104 a, 104 b, 104 c and 104 d via an extravascularoperation. Thereafter, plugs 108 a, 108 b, 108 c and 108 d are insertedinto or over respective apertures in anterior coronary artery wall AWaligned with passageways 104 a, 104 b, 104 c and 104 d and stents 106 a,106 b, 106 c and 106 d. As illustrated in FIG. 13, a patch 110 may beplaced over coronary artery CA and particularly over plugs 108 a, 108 b,108 c, 108 d and attached via sutures 112 to heart PH to brace the plugsagainst dislodgment under systolic and diastolic blood pressures.

FIGS. 14A and 14B depict steps in a transmyocardial revascularizationprocedure. An incising instrument 114 such as a laser fiber or a drillis inserted in an extravascular procedure through an open chest incisionor a pericardioscopic cannula or port and is used to form a channel orpassageway 116 in heart wall or myocardium HW through the epicardium(not shown). A stent 118 is inserted into channel 116 in a collapsedconfiguration via an intravascularly deployed catheter 120 or in anextravascular operation. A plug 122 is inserted into an outer end ofchannel 116 to close off that outer end. Plug 122 may be attached to theepicardium of heart PH via a laser instrument 123 or via sutures (notshown). Several channels 116, 116 a and 116 b may be formed and providedwith respective stents 118, 118 a and 118 b and respective plugs 122,122 a and 122 b, as illustrated in FIG. 15. A patch 124 may be placedover plug 122 or plugs 122, 122 a and 122 b and attached via sutures 126to heart wall HW.

Myocardial Plugs

The various conduits or stents disclosed herein may be provided with alayer of polymeric material carrying a biochemical composition, e.g.,angiogenesis factor or the nucleic acid instructions therefor, forgenerating, stimulating, and enhancing blood vessel formation. Asillustrated in FIG. 16, plugs 128 may be inserted into a patient's heartwall or myocardium HW from inside the left ventricle LV or rightventricle RV via an intravascularly deployed catheter (not shown).Alternatively, the plugs may be inserted into the heart wall ormyocardium HW from outside of the heart in an open incision orpericardioscopic operation (not shown). In either case, the plugs carryangiogenesis factor, or the nucleic acid instructions therefor, forgenerating, stimulating, and enhancing vascular generation and growth.The angiogenesis factor is gradually released from the plugs, or stents,in time release fashion, to optimize the stimulation of vascular growth.

FIG. 16A is a schematic partial cross-sectional view of atriangular-shaped conduit comprising a plug 940 or stent or the like andhaving, for example, multiple factors applied thereto such as growthfactors, genes, drugs, etc. The rate at which an applied factor isreleased may be controlled through appropriate configuration of the plug940, e.g., by controlling its porosity.

If desired, the stent or conduit of the present invention can be formedof biodegradable or bioabsorbable materials and/or used to deliver drugsdirectly into the myocardium and the coronary circulation. Such a stent952 is illustrated in FIG. 16B. The biodegradable stent 952 can extendonly partially through the heart wall HW as illustrated in FIG. 16B, butcan also extend entirely through from the left ventricle LV to thecoronary artery CA. Once positioned in the heart wall HW, the stent 952degrades, dissolves or is absorbed over time to release drugs, genes,angiogenesis or growth factors, or other pharmaceutical compoundsdirectly into the heart wall HW and the coronary artery CA, as shown bythe arrows in FIG. 16B. Bioabsorbable materials include, but are notlimited to, polymers of the linear aliphatic polyester and glycolidefamilies, such as polylactide and polyglycolide.

Such a stent is also illustrated in FIGS. 16C–16F. FIG. 16C illustratesthe external insertion of a solid, but absorbable stent or plug 1100. Adelivery device 1102, such as a thoroscope bearing the intramyocardialplug 1100 is inserted into the heart wall HW at a site distal to theblockage BL in the coronary artery CA as shown in FIG. 16D. Theinsertion site in the heart wall HW is permanently closed using sutures1104, a plug, laser coagulation or similar means, as shown in FIG. 16E.This allows for myocardial revascularization. As the plug 1100 isabsorbed, blood flows from the coronary artery CA into the passagewayformed by the absorbed plug 1100. This results in the ischemicmyocardial area being revascularized. Alternatively, as illustrated inFIGS. 16E and 16F, the intramyocardial plug 1100 can be inserted throughthe heart wall HW such that it extends into the left ventricle LV. Asthe plug 100 is absorbed by the body, there remains a space or channel1106 in the heart wall HW that perfuses with oxygenated blood from theleft ventricle LV. This channel 1106 acts as do the channels formed inthe heart during percutaneous transmyocardial revascularization (PTMR),allowing the heart muscle to be exposed to additional oxygenated blood.

FIGS. 16G–16I illustrate an alternative means for delivering anabsorbable plug 1110 into the heart wall HW. FIG. 16G illustrates thedelivery of multiple plugs 1110 using a catheter 1112 threaded throughthe patient's vasculature and into the left ventricle LV of the heart.The plug 1110 is inserted into the myocardial wall as shown is FIG. 16H.The plug 1110 is absorbed over time, leaving an opening or channel 1114in the heart wall HW (FIG. 16I) that perfuses with oxygenated blood fromthe left ventricle LV. This channel 1114 acts as do the channels formedin the heart during percutaneous transmyocardial revascularization(PTMR), allowing the heart muscle to be exposed to additional oxygenatedblood.

Turning now to FIGS. 16J–16N, there is shown the insertion of anabsorbable intramyocardial plug 1120 that achieves the same result as astent. The plug 1120 is inserted through the posterior wall of thecoronary artery CA, either externally as described below, or internallyusing a delivery catheter threaded through the aorta AO and the coronaryartery CA. External insertion is illustrated in FIGS. 16J–M. In FIG.16J, there is illustrated a thoroscope 1122 having the absorbable plug1120 at its distal end inserted into the chest of the patient, until itreaches the heart. The plug 1120 is inserted through the posterior wallof the coronary artery CA and into the heart wall HW (FIGS. 16K and16L). As the delivery device 1122 is removed, the hole in the anteriorwall of the coronary artery CA is closed, using sutures 1124, staples,laser coagulation, plugs such as GELFOAM, adhesives such ascyanoacrylate, or similar closure means, as illustrated in FIG. 16M. Asthe plug 1120 is absorbed, a shunt 1126 is formed between the leftventricle LV and the coronary artery CA, which allows for the passage ofblood (FIG. 16N).

FIGS. 16O–16S illustrate the insertion of absorbable intramyocardialplugs 1130 which result in the perfusion of the heart wall HW with bloodflowing through the coronary artery CA. In FIG. 16O, there isillustrated a thoroscope 1132 having the absorbable plug 1130 at itsdistal end being inserted into the chest of the patient, until itreaches the heart. The plug 1130 is inserted through the posterior wallof the coronary artery CA, and only partially through the heart wall HWsuch that it stops before reaching the left ventricle LV of the heart(FIG. 16Q). As the delivery device 1132 is removed, the hole in theanterior wall of the coronary artery CA is closed, using sutures 1134,staples laser coagulation, plugs, such as GELFOAM, adhesives such ascyanoacrylate or similar closure means, as illustrated in FIG. 16R. Theplug 1130 is absorbed over time, leaving an opening or channel 1136 inthe heart wall HW (FIG. 16S) that perfuses with oxygenated blood fromthe coronary artery CA. The channel 1130 acts as do the channels formedin the heart during percutaneous transmyocardial revascularization(PTMR), allowing the heart muscle to be exposed to additional oxygenatedblood.

It is to be appreciated that the drawings herein are schematic. Thestents and shunt portions in the forms of stents described herein mayhave a conventional wire infrastructure not shown in the drawings.Alternatively, the stents may be made of an elastic material having aninternal spring constant permitting the stent to be temporarilycollapsed and then returned to an opened configuration.

Intravascular or extravascular incising instruments disclosed herein foruse in forming passageways or channels in the myocardium may be contactlasers or rotating or reciprocating drills. Other drilling or cuttinginstruments suitable for forming channels or tunnels may be usedalternatively or additionally. Such instruments may take the form ofultrasonic cavitation devices, chemical devices for dissolving tissues,or heat treatment (electrocautery) devices.

Although suturing, gluing and laser welding are discussed herein forattaching plugs and reinforcement patches or braces to the cardiactissues, equivalent alternatives to these techniques include staplingand tacking. Also, apertures in the epicardium or coronary artery may beclosed without plugs or patches, for example, by the direct applicationof sutures or staples or by coagulation (electrical, thermal or laser).

It is to be understood that stents are preferred for maintaining openblood flow passageways in or through the myocardium. However, in somecases, stents may be omitted, for example, in the embodiments of FIGS.10C, 11, 12, 14A and 14B and 15, depending on the needs of the patient.

Generally, stent 36 (FIG. 3), upstream portion 56 (FIGS. 6A, 6B) when inthe form of a stent, stent 70 (FIG. 8), plugs 98, 98 a, 98 b (FIG. 11),stents 106 a–106 d (FIG. 12), and plugs 122, 122 a, 122 b (FIG. 15) havelengths which are predetermined by measuring the thickness of themyocardium. Procedures for such measurements are described in U.S. Pat.Nos. 5,429,144 and 5,662,124, the disclosures of which are herebyincorporated by reference in their entirety.

Self-Inserting Conduits

As is well known, the coronary artery CA branches off the aorta AO andis positioned along the external surface of the heart wall HW.Oxygenated blood flows from the heart PH to the aorta AO, into thecoronary artery CA, and on to the rest of the body. In some individuals,plaque builds up within the coronary artery CA, blocking the free flowof blood and causing complications ranging from mild angina to heartattack and death.

In view of restoring the flow of oxygenated blood through the coronaryartery CA, embodiments are disclosed which provide for the shunting ofblood directly from the heart to a site in the coronary artery CA whichis distal to the blockage BL. In a similar manner to that describedabove, a single rod-like conduit may utilize posterior heart wall accessin order to be inserted through the walls of the coronary artery CA andthe heart wall HW, and from there into the left ventricle LV of theheart PH which lies beneath the coronary artery CA. The hollow conduitis positioned such that the openings on either end of the conduit arewithin the coronary artery CA and the left ventricle LV. Blood flowsthrough the opening in the left ventricle LV, through the hollow conduitand out of the opening positioned in the coronary artery CA distal tothe site of the blockage BL. Thus, the self-inserting conduit ispreferably rigid or at least semi-rigid in order to provide the abilityto pierce through the heart wall or other tissue of the patient and toinstall the conduit as described above. In this case, the conduit ispreferably a delivery rod in that it provides for its own delivery.

Referring to FIG. 17, there is shown a cross-sectional view of a typicalheart PH, aorta AO, and the coronary artery CA having a blockage BLtherein. The coronary artery CA lies along the external surface of thewall of the heart HW. As is well known, the coronary artery CA suppliesoxygenated blood pumped from the left ventricle of the heart LV andthrough the aorta AO to the heart muscle or heart wall HW.

FIG. 17 also illustrates in schematic fashion a bypass device 210implanted distal to the blockage BL in the coronary artery CA. It shouldbe noted that only the presently preferred embodiments of the bypassdevices are described herein and only then in accordance with certainfigures. However, arteries and vessels other than the coronary artery CAmay be treated. As used herein, the term “vessel” shall be deemed toembrace any body organ, vessel, space or vasculature, includingartificial members or prior implants, which contains or can containbodily fluid. In addition, other types of blockages or vascular defectscan be treated, including, for example, vascular bypass in other areasto alleviate problems such as aneurysms, deep vein thrombosis, or othertypes of calcified or stenosed vessels. Embodiments described herein maybe used to bypass obstructed bile ducts in the liver, or to direct theblood supply away from tumors in an effort to destroy them. Accessdevices using configurations other than conduit devices as hereindescribed, may also be implemented. Thus, the following descriptionshould not be construed to be limiting in any way.

Referring to FIG. 18, there is shown in greater detail one preferredembodiment of the bypass apparatus 210 of the present invention. Theapparatus 210 is preferably formed of a biocompatible material, such asmetal or a polymer. The apparatus 210 is shown piercing the coronaryartery CA distal to the site of the blockage BL. The details of thisconduit device 210 are described below. In connection with the somewhatschematic representation of FIG. 18, it will be noted that the device210 pierces completely through the coronary artery CA, with the centralportion 212 of the device 210 positioned within the myocardium HW andthe distal portion 214 of the device 210 implanted in the left ventricleof the heart LV.

Each shunt device 210 (FIG. 18) is comprised of a central portion 212formed by a hollow lumen having respective aperture or openings 216, 218on each end. One opening 216 receives blood from the left ventricle LVand shunts it through the lumen and out the other opening 218 which ispositioned in the coronary artery CA. The conduit 210 therefore allowsoxygenated blood to flow directly from the left ventricle LV and intothe coronary artery CA, as indicated by the arrows 219 a and 219 b inFIG. 18.

The distal end of the conduit 214 may be blunt (FIG. 20B) or tapered ifdesired (FIG. 18) to aid in the insertion of the device 210 through thecoronary artery CA, the heart wall HW and the left ventricle LV. Theproximal end 220 of the conduit 210 is preferably provided with a headportion 222 that is larger than the diameter of the lumen (FIG. 18), tohelp anchor the conduit 210 in place and prevent it from migrating orpassing completely through the coronary artery CA. This head portion 222also acts to seal the puncture in the coronary artery CA formed by thedistal tip 214 of the conduit 210. The blood therefore flows through theconduit 210 and downstream within the coronary artery CA and not outthrough the puncture opening. If desired, the head portion 222 of thedevice 210 may be sutured into the surrounding tissue to prevent thedevice 210 from migrating from its proper position. Additional anchoringin the form of sutures or other means 224 is also preferably providedalong the central portion 212 of the conduit 210. Anchoring the device210 into the myocardium HW prevents migration of the conduit 210 fromits proper position.

As illustrated in FIG. 18, the conduit 210 may also include a secondopening 225 at its proximal end 220 opposite from the first opening 218.This second opening 225 allows for the perfusion of blood from thecoronary artery CA as shown by the arrow 221 in FIG. 18, i.e., if theblockage BL does not completely block the coronary artery CA, blood mayperfuse past the blockage BL and through the second opening 225. FIG.18A illustrates a self-inserting conduit having a flange or head withdual prongs 227 to prevent rotation of the conduit in the coronary, toensure proper blood flow through the opening 218.

In installing the device of this embodiment, the surgeon may make asmall incision of a keyhole type in order to gain access to the blockedvessel. Visual access may be obtained through thoroscopy or similarendoscopic procedure. Such access is very minimally invasive. Once thearea of blockage is located (through fluoroscopy, etc.), the conduit 210is implanted in the body in the manner described above. The conduitdevice 210 is preferably introduced by way of an automatic gun or needlein order to reduce procedure time and avoid bleeding, but the conduit210 may be implanted in other ways as well.

One method for implanting the device is illustrated in FIGS. 19A–C. Theconduit 230 is first mounted over a needle 232 (FIG. 19A), and theneedle 232 is used to puncture the coronary artery CA, heart wall HW andleft ventricle LV (FIG. 19B). The distal end of the needle 232 isindicated by reference numeral 233. The needle 232 is then removed (FIG.19C) and the anterior hole in the coronary artery CA is closed usingsutures 234 or other suitable methods.

In an alternate method illustrated in FIGS. 20A and 20B, a flap FL isfirst cut in the wall of the coronary artery CA and the needle 232bearing the conduit 230 is inserted through the flap FL and through theother side of the coronary artery CA, through the heart wall HW, andinto the left ventricle LV. The needle 232 is withdrawn, leaving theconduit 230 in place. The flap FL is then closed using sutures 234 orother suitable means.

The conduit 230 is preferably anchored in place in the heart wall HW asdescribed above to prevent migration and to ensure that the free flow ofblood from the left ventricle LV to the coronary artery CA ismaintained.

Coronary Bypass

Referring to FIG. 21, there is shown a cross-sectional view of a typicalheart anatomy including the aorta AO with a blockage BL or stenosis inthe coronary artery CA which is positioned along the external surface ofthe heart wall HW. As is well known, the coronary artery CA suppliesblood pumped from the left ventricle LV to the aorta AO and into theheart muscles or myocardium HW.

FIG. 21 also illustrates in schematic fashion a bypass device 310mounted both proximally and distally of the blockage BL by means ofconduit combination access/shunt devices 312 and bypass conduit 314,described in more detail below.

Referring to FIG. 22, there is shown in greater detail one preferredembodiment of the bypass apparatus 310. The apparatus 310 is preferablyformed of a biocompatible material, such as metal or a polymer. A pairof combination access/shunt devices 312 is shown proximally and distallyof the blockage BL. The details of these conduit devices 312 aredescribed below and shown in connection with FIGS. 24 and 25. Inconnection with FIG. 22, it will be noted that each access/shunt device312 pierces completely through the coronary artery CA on the outside,leaving the conduit portion 316 of the device 312 implanted in the wallof the heart wall HW. The conduit portion 316 pierces not only throughthe coronary artery CA, but also into the tissue to provide anchoringand stabilization of the artery. The conduit portion 316 can be embeddedin a tissue or passed completely through the tissue and into the leftventricle LV as shown in the portion of the device distal to theblockage BL.

FIGS. 22A–22B illustrate two alternative embodiments for conduits of thenature described above. In FIG. 22A, the conduit is preferably placedproximally in the coronary artery CA to preferably allow some of theproximal flow in the coronary artery CA through the conduit and past theblockage BL to a downstream location in the coronary artery CA. Thisembodiment is preferably utilized in connection with blockages which arenot complete, and yet advantageously also allows for bypass flow asdescribed above. The conduit of FIG. 22B, however, does not allow anyproximal flow through the coronary and all flow is diverted through thebypass.

Each access/shunt device 312 (e.g., see also FIG. 24) is comprised of ashunt portion 318 having an aperture 320 which, in the case of theproximal device, receives blood from the coronary artery CA and shuntsit into a diversion tube 322 mounted proximally with respect to theconduit portion 316 and the aperture 320. The diversion tube 322 is influid communication with the aperture 320 to allow blood flow from thecoronary artery CA into the aperture 320 and into the diversion tube 322as indicated by the arrows in FIG. 22. Mounted proximally with respectto the diversion tube 322 is a connector piece 324 which is also influid communication therewith. The combination access/shunt device 312which is distal of the blockage BL may be constructed in a similarfashion or may have another configuration in which blood flows in thedirection opposite that indicated by the arrows in FIG. 22. The bypassconduit 314, which is hollow, is mounted on the two connector portions324 of the devices 312, as shown in FIG. 22, to allow blood to bypassthe blockage BL. The conduit 314 may be constructed from a vein orartery graft taken from the patient or a donor, an artificial veingraft, or any other biocompatible tubing including one made from a metalor polymer. All these connections are fluid-tight, as described below inmore detail, to avoid hemorrhaging. FIG. 22 illustrates the conduitportion 314 somewhat exploded away from the connector portions 324 inorder to illustrate the manner in which the complete bypass system canbe assembled.

FIG. 23 illustrates the conduit portion 314 of the bypass system 310completely press-fit or snapped-down over the connector portions 324(not shown in FIG. 23), as is the case in the final installation of thesystem.

FIG. 24 illustrates the combination access/shunt device 312 in greaterdetail. The distal conduit portion 316, as described above, providesaccess to the coronary artery CA by piercing completely through and intothe surrounding tissue. A barbed distal portion 326 having one or morebarbs provides anchoring for the entire device. The proximal shuntportion 318 which resides in the vessel comprises the aperture 320 toallow blood to flow therein and from there, at a right angle, into thediversion tube 322 mounted proximally with respect to the aperture 320,as indicated by the arrow in FIG. 24. The proximal shunt portion 318 maybe tapered if desired to aid in the insertion of the device 312 throughthe coronary artery CA and into the heart wall HW. Mounted on top of thediversion tube 322 is a connector tube 324 for receiving the bypassconduit 314 as described above. It will be noted that the connector tube324 is frusto-conical in order to provide a fluid-tight press-fit forthe bypass.

In a preferred embodiment, a biocompatible fabric or mesh (not shown) isincorporated into the structure of the device. This fabric or mesh helpsto seal the vessel to prevent bleeding and provides a structure whichallows endothelial cells to infiltrate the device 312 and incorporate itinto the surrounding tissues.

Likewise, FIG. 24 illustrates an inverted U-shaped saddle portion 328 ofthe device 312 which serves a dual purpose. This saddle portion 328 fitsover the artery when the combination access/shunt device 312 isinstalled therein, thereby stabilizing the artery. In addition, thissaddle device 328 acts as a flange for self-sealing the puncture in thecoronary artery CA formed by the barbed distal tip 326. In addition, thecollar or saddle that may help contain the artery and mitigate anypossible migration problems. Thus, blood flows through the diversiontube 322 and not out through the puncture opening. If desired, a loopmay be added to the saddle portion 328 to allow the device to be suturedinto the myocardium HW to prevent the device from migrating from itsproper position.

FIG. 25 is an alternative embodiment of the conduit access/shunt deviceof FIG. 24 in which a planar flange 330 serves to stabilize the arteryand to self-seal the puncture therein.

FIGS. 27 and 28 show views of two additional embodiments for device 312.FIG. 27 shows device 312 having a tapered configuration to aid in theinsertion of the device 312. FIG. 28 shows a device 331 having dualdistal tips to prevent rotation of the device when installed in thetissues of the patient.

In installing the device 310, the surgeon may make a small incision of akeyhole type in order to gain access to the blocked vessel. Visualaccess may be obtained through thoracoscopy or similar endoscopicprocedure. Such access is very minimally invasive. Once the area ofblockage is located (through fluoroscopy, etc.), one or both of thecombination access/shunt devices 312 are installed in the artery in themanner described above. The conduit devices 312 would preferably beintroduced by way of an automatic gun which would implant both conduitdevices 312 and the conduit 314 at the same time in order to reduceprocedure time and avoid bleeding. Alternatively, the conduits 312 couldbe introduced individually, provided that bleeding is controlled.

The device 310 can be sutured in place to provide for permanent bypass;alternatively, the device can be implanted temporarily to maintain theflow of blood through the coronary artery CA during bypass surgery. Thedevice 310 is implanted as described above. A vein graft is sutured inplace, with one end anastomosed to the aorta, and the other end to thecoronary artery CA at a site distal to the blockage. The device 310provides blood flow from the aorta to the coronary artery CA at a sitedistal to the blockage BL during the anastomosis. Once blood flow hasbeen established through the vein graft, the bypass device may beremoved.

FIG. 29 illustrates a further embodiment of the combination access/shuntdevice 312. The distal conduit portion 316, as described above, providesaccess to the coronary artery CA by piercing completely therethrough andinto the surrounding tissue. The barbed distal portion 326 having one ormore barbs provides anchoring for the entire device. The proximal shuntportion 318 which resides in the vessel comprises an aperture 320 toallow blood to flow therein and from there, at a right angle, into thediversion tube 322 mounted proximally with respect to the aperture 320.The proximal shunt portion 318 may be tapered if desired to aid in theinsertion of the device 312 through the coronary artery CA and into theheart wall HW. Mounted on top of the diversion tube 322 is a connectortube 324 for receiving a bypass conduit as described above. It will benoted that the connector tube 324 can be frusto-conical in order toprovide a fluid-tight press-fit for the bypass. In a preferredembodiment, a biocompatible fabric or mesh (not shown) is incorporatedinto the structure of the device. This fabric or mesh helps to seal thevessel to prevent bleeding and provides a structure that allowsendothelial cells to infiltrate the device 312 and incorporate it intothe surrounding tissues. A planar flange 330 serves to stabilize theartery and to self-seal the puncture therein.

FIG. 30 illustrates a further embodiment of the combination access/shuntdevice 312. The distal conduit portion 316, as similar to that describedabove with respect to other embodiments, and has a barbed distal portion326 having one or more barbs for anchoring the device. The proximalshunt portion 318 which resides in the vessel comprises an aperture 320to allow blood to flow into the diversion tube 322. The proximal shuntportion 318 may be tapered. The top of the diversion tube 322 forms atapered connector portion 324 for receiving a bypass conduit asdescribed above. It will be noted that the connector portion 324 can befrusto-conical. In a preferred embodiment, a biocompatible fabric ormesh (not shown) is incorporated into the structure of the device, asabove. A planar flange 330 serves to stabilize the artery and toself-seal the puncture therein. Attached to the planar flange anddistributed thereabout are one or more retaining members 323, which cancomprise detents at the end thereof for engaging the bypass conduit. Thedetents can be in the form of hooks, clasps, split rings, pads, or thelike in order to mechanically retain the bypass conduit onto theconnector portion 324 of the diversion tube 322.

Referring now to FIG. 31, the shunt device 312 of FIG. 29 is depicted incross-section, where like features are referred to by the same referencenumerals. The view depicts the device 312 inserted into an artery, suchas the coronary artery CA of a patient, and further depicts a blockageBL therein. A bypass conduit, for example, a vein or artery graft 314,is secured to the connector tube 324 of the diversion tube 322 above theflange 330. Optionally, an access port or hole may be placed along theshunt body opposite the aperture 320 at portion 332 to increase totalflow and to maintain blood perfusion through the vessel bypassed. Italso should be noted that although the figure depicts the device 312inserted perpendicular to the artery CA, the geometry of the device 312allows it to be inserted at an angle without affecting its performance.This feature advantageously allows for more flexible application of thedevice during surgery, where perpendicular access to a vessel is notalways available or convenient. FIG. 32 presents a view similar to thatof FIG. 31, showing the barb 326 of the conduit device implanted in themyocardium HW of a patient for perfusing the coronary artery CA.

A side-by-side bypass device 412 is depicted in FIG. 33, and FIG. 33Aillustrates in schematic fashion the bypass achieved with the conduit ofFIG. 33. In this case, the bypass conduit runs more parallel to thecoronary artery CA and therefore utilizes less space within theintrapericardial space. In this device, the distal conduit portion 416is similar to that described above with respect to other embodiments,and has a barbed distal portion 426 having one or more barbs foranchoring the device. The proximal shunt portion 418 which resides in avessel comprises an aperture 420 to allow blood to flow into thediversion tube 422. The aperture 420 passes through the shunt portion418, and allows communication with the diversion tube to either side ofthe shunt portion 418. The proximal shunt portion 418 may be tapered.The top of the diversion tube 422 forms a connector portion with asecond aperture 421 for communicating with a bypass conduit, such as anartery or vein graft. As above, a biocompatible fabric or mesh (notshown) can be incorporated into the structure of the device. A planarflange 430 serves to stabilize the artery and to self-seal the puncturetherein. Similarly, a flange 434 is provided at the end of the diversiontube 422 to self-seal the puncture in the artery or vein graft.

FIG. 34 depicts an alternative embodiment 412′ similar to the device ofFIG. 33. The device of FIG. 34 has an aperture 420′, which extendsthrough only one side of the shunt portion 418′. It should be understoodthat the apertures of this and the preceding embodiment may beselectively placed and sized according to the desired application, theorientation of the blood vessels employed, and the location ofanatomical features, blockages, etc.

FIG. 35 depicts a further alternative embodiment 412″ that is similar tothe embodiment depicted in FIGS. 33 and 34 except that there is noflange between the apertures 420 and 421, but rather a smooth transitionarea 430″. The shunt body 418″ is shown to have a gentle taper.

FIG. 37 is a cutaway schematic representation of the shunt device 412′depicted in FIG. 34 mounted within the patient, with the conduit endresident within the myocardium HW. The coronary artery CA and the bypassgraft 414 are shown to be placed in fluid communication by the apertures420′, 421 in the shunt 412′. This illustration is illustrative of allside-by-side instant anastomosis devices described herein. Further, itshould be noted that a hole may be located at position 436 to allowadditional perfusion of the coronary artery CA, and that the aperture420′ could pass through both sides, as in devices 412 and 412″. Further,it should be noted that the device could be mounted at an angle, asdiscussed hereinabove.

FIG. 38 is a cutaway schematic representation of a “rivet” type shuntdevice 512 mounted within the patient, with the retention members 540deployed. A flange 534 seals the incision and maintains a bearingsurface against the bypass graft 514, which could be venous or arterial.An aperture 520 opens a channel into the hollow stent body 518, whichterminates in an open end 542. In this illustrative arrangement, theopen end 542 is resident within the coronary artery CA.

For illustrative purposes, it has been found that an anastomosis shuntdevice of the type depicted in FIG. 29 can be dimensioned to have aheight of 12.5 mm, with a body width of about 2 mm, a flange diameter ofabout 2.8 mm, and an inside diameter of the diversion tube of about 1.4mm. The conduit can be dimensioned to be about 3 mm in height taperingto a width of about 2.1 mm. The aperture can be dimensioned to be about1.4 mm in diameter, and can have an edge radius about the periphery ofabout 0.10 mm all around. An anastomosis shunt device of the typedepicted in FIG. 33 can be dimensioned to have a height of 12.65 mm,with a body width of about 2.8 mm, a flange diameter of about 3.4 mm,and an inside diameter of the diversion tube of about 2.0 mm. Theconduit can be dimensioned to be about 3 mm in height tapering to awidth of about 2.6 mm. The apertures can be dimensioned to be about 2.0mm in diameter, and can have an edge radius about the periphery of about0.10 mm all around.

Anastomosis Devices and Methods

It will be noted in connection with the coronary bypass devices,systems, and methods described above that various connections from oneconduit to another are necessary. The term “anastomosis” refers to thejoining of two conduits or two vessels in a similar fashion; although,in the context of the present application, that term should not belimited to a particular medical definition or practice, but refersbroadly to the connection of various conduits in connection with bypasssystems. Thus, as described above, prefit connections from one conduitonto a hub of another conduit are possible, although other anastomosisconfigurations are described below.

As shown in FIGS. 39A and 39B, a conduit 600 can be used to providetemporary blood flow during therapeutic procedures. For example, intypical coronary artery bypass surgery, a section of vein VG taken fromthe leg of the patient is attached at one end to the aorta AO and at theother end to a point distal to the blockage in the coronary artery CA.This surgery requires the delicate procedure of joining the vein graftVG to the aorta AO and to the coronary artery CA. This joining of theblood vessels is known as anastomosis. Normally, the patient is placedon a heart-lung machine to keep the blood oxygenated and flowing duringthis procedure, and the blood is diverted from the coronary artery CA toallow the physician to complete the anastomosis.

In one embodiment of the present invention, the conduit 600 is used tomaintain blood flow through the coronary artery CA during bypass surgery(FIG. 39A). The vein graft VG is loaded on top of the stent 600 prior toimplantation. The conduit 600 is implanted as described above, at thepoint of the vein graft VG anastomosis. The vein graft VG is sutured tothe aorta and to the CA at a point distal to the blockage BL. Ifdesired, the sutures can be preloaded onto the graft VG to facilitatethe anastomosis. Once the vein graft VG has been attached, the conduit600 is removed, and blood flow occurs from the aorta AO, through thevein graft VG, and down the coronary artery CA. The conduit 600 can besutured in place during the anastomosis procedure for permanentattachment, if desired.

Other embodiments for connecting vessels or segments of vessels togetherare shown in FIGS. 40–40G. FIG. 40 illustrates two vessels 1200 and 1202to be connected to respective disc members 1210 and 1212. Each of thedisc members 1210 and 1212 includes a plurality of prongs 1220 which areconfigured to mate with opposing holes 1224. After the disc members1210, 1212 are secured to the vessels 1200 and 1202 (FIG. 40A), thevessels 1200 and 1202 may be effectively joined by snapping or lockingthe disc members together. As illustrated in FIG. 40B, this may be doneby aligning the prongs 1220 with the holes 1224, so that the prongs passthrough and are accepted by the holes.

A technique for securing the vessels 1200 and 1202 to the disc membersis illustrated in FIGS. 40C–40G. FIG. 40C shows the vessel 1200 (e.g., aleft internal mammary artery or “LIMA”) being brought into proximitywith a disc member 1226, which, as shown in FIG. 40D, is brought overthe vessel 1200, so that a portion 1230 of the vessel 1200 extendsbeyond the disc member 1226. As shown in FIG. 40E, the portion 1230 maythen be advantageously everted over the disc member 1226, so that theprongs 1220 of the disc member 1226 pierce through the vessel portion1230. As illustrated in FIGS. 40F and 40G, the disc member 1226 may thenbe mated with another disc member 1234 having a plurality of holes 1224therein. The disc member 1234 may advantageously be part of a largerintegrally formed conduit device 1240 for redirecting the flow of bloodaround a blockage BL (not shown in FIG. 40F) within the coronary arteryCA. A spike 1250 may be used to secure the conduit device 1240 withinthe heart wall HW. Although the disc member 1226 is shown as havingseveral prongs 1220 that mate with respective holes 1224 in another discmember 1234, it will be understood that disc members having alternateholes and prongs (like those in FIGS. 40–40B) may be used.

Another conduit device 1254 is shown in FIG. 40H, in which the device1254 includes a disc member 1234 that mates with another disc member1226. The conduit device 1254 is held snugly within the coronary arteryCA by a rim element 1258 of the device 1254. In FIG. 40I a conduitdevice 1260 is shown that includes a spike 1262 for securing the device1260 into the heart wall HW. A vessel 1200 fits around a cylindricalportion 1264 of the conduit device 1260 and is held around thecylindrical portion 1264 by friction or with a ligature 1268.

FIG. 40 J shows a conduit member 1280 having a pair of rings 1282 and1284. As shown in FIG. 40 K, one of the rings 1282 fits snugly insideand against the wall of the coronary artery CA, while the other ring1284 sits above and on top of the coronary artery CA. A vessel 1200 fitsover the ring 1284 and may be held in place with a suture 1286.

FIG. 40L shows another conduit member 1290, a base 1292 of which restson the coronary artery CA, as illustrated in FIG. 40M. A suture 1286 maybe used to secure the vessel 1200 to a ring 1294 of the conduit member1290.

FIG. 40N shows another conduit member 1300 which functions similar toits counterpart in FIG. 40L, except that instead of a ring 1294, aplurality of teeth 1304 are used for holding the conduit member 1300 inplace. Specifically, a vessel is brought over the conduit member so thatthe vessel slides beyond the teeth 1304. As the vessel 1200 is thenretracted, the teeth 1304 engage the vessel 1200, thereby securing thevessel 1200 to the conduit member 1300, as shown in FIG. O.

Another conduit member 1320 is shown in FIG. P. The member 1320 includesa ring 1324 and a plurality of teeth 1328. When in use, the ring 1324contacts the inside of the coronary artery CA, whereas the teeth 1328engage the vessel 1200 in a manner analogous to the embodiment of FIGS.40N–O.

Conduits with Flow Resistance

One of the advantages of certain embodiments of the present conduits isthat they can be designed to optimize fluid or blood flow through them.That is, the design or configuration of a conduit may be such that itautomatically achieves flow control without microvalves, check valves,or other moving devices. (See, for example, the conduits of FIGS. 6A–Hand 8–8P.) Such moving or articulating devices may be complicated orexpensive to manufacture, particularly on the small scales required inthis context. Thus, in one embodiment, flow control is achieved bymaximizing flow through the conduit in one direction (preferably fromthe left ventricle to the coronary artery), but minimizing flow throughthe conduit in the opposite direction. Since flow rate through theconduit is a function of friction or drag, turbulence, and other fluiddynamic parameters, it may be convenient to discuss flow rate throughthe conduit in terms of resistance of the conduit to such flow. In otherwords, in one embodiment, it is advantageous to have a low conduitresistance in the forward direction (from the left ventricle to thecoronary artery), but a higher resistance in the opposite direction. Inthat sense, the conduit acts as a type of choke device having a higherreversed flow resistance or diastolic resistance than the forward flowor systolic resistance.

Experimentation has shown, however, that the above characteristics maynot necessarily produce optimized flow rate in the coronary artery.Thus, it should be remembered that flow rate through the conduit shouldbe controlled such that it enhances total coronary flow rate, whichtotal coronary flow rate is essential for perfusion of the hearttissues. Thus, experimentation has shown that the degree of proximalocclusion may have an effect on total coronary flow rate. It has beendetermined that, where a proximal occlusion is only partial, the totalflow rate in the distal coronary artery may increase with greatersystolic resistance in the conduit. This may be due, at least in part,to the back pressure which the flow through the conduit sees as a resultof the partial occlusion. Thus, optimization under these circumstancesmust take into consideration the degree of proximal occlusion. In thisregard, it has been determined that total coronary flow rate isincreased with increasing systolic resistance through the conduit.Preferably, diastolic resistance remains high. For example, it has beenfound that with mild systolic resistance, an increase in coronary flowrate was achieved with approximately zero negative diastolic flow.

Thus, referring to FIG. 41, there is shown in schematic, cross-sectionalview a conduit 1400 which has been designed to achieve flow optimizationunder certain circumstances, and which acts as an asymmetrical flowresistor. In this case, the conduit 1400 is generally curved withvarying wall thickness, and has a proximal end 1404 which extends intothe left ventricle LV and a distal end 1408 which curves so that itsexit is approximately transverse to the direction of flow in the distalportion of the coronary artery CA. In this context, the term “distal” isused with respect to direction of flow and represents a locationdownstream from a given point in the flow path. It will be observed thatthe proximal portion of the conduit 1400 shown in FIG. 41 extends intothe left ventricle LV to take into consideration the changing wallthickness of the myocardium. Thus, the proximal portion of the conduit1400 may extend into the ventricle LV roughly 5%–30% to accommodate forsuch changing wall thicknesses. Thus, during systole, the myocardium HWcontracts and goes into tension, thus increasing the thickness of themyocardium. The conduit 1400 of FIG. 41 is designed to accommodate sucha thickening such that its entrance 1412 will be approximately flushwith the internal surface of the myocardium HW during systole.

It will also be observed at the proximal end 1404 of the conduit 1400that the entrance 1412 is shaped so as to have a high radius ofcurvature, which is approximately ½ of the difference between thediameter at the exit 1416 and the diameter of the conduit 1400 at theentrance 1412. This curvature tends to reduce flow losses (or in otherwords, decreases resistance to flow) at the entrance 1412, therebymaximizing flow through the conduit during systole. At the same time, itwill be observed that the decreased diameter at the entrance 1412increases the resistance to reverse diastolic flow at that location,thus tending to decrease negative flow through the conduit 1400 or flowfrom the coronary artery CA back into the ventricle LV. Thus, theproximal portion of the conduit 1400 is designed so as to achieve anabrupt expansion resulting in large exit losses and consequently highresistance to diastolic flow.

At the distal end 1408, on the other hand, flow losses are minimized, soas to minimize flow resistance. Such exit losses are essentially zerobecause the exit diameter of the conduit 1400 proximates or matches thediameter of the coronary artery CA. Moreover, during diastolic flow,there will be an “entrance” losses at the exit of the conduit 1400, thusincreasing the resistance to such negative flow. Moreover, the curvedconfiguration of the distal end 1408 of the conduit 1400 minimizes flowloss during diastole which results from proximal flow through a partialocclusion. In other words, the distal end 1408 of the conduit 1400 canbe constructed so as to allow a proximal flow passing a partialocclusion and contributing to the flow through the conduit 1400 toproduce an advantageous total coronary flow rate. Such distal designsfor the conduit 1400 are described elsewhere herein and are compatiblewith the conduit of FIG. 41. Moreover, the conduit 1400 can beconstructed from a rigid or flexible material, it may be a solid wall orlattice structure (e.g., stent-like) as described below.

Thus, the conduit 1400 of FIG. 41 can be designed so as to optimizetotal flow rate by designing a certain flow resistance through theconduit 1400 in accordance with the conditions indicated by the patient.In this embodiment, the wall thickness of the conduit 1400 varies by ataper (θ) of approximately 4°, thus producing the differences inentrance and exit diameters. This degree of taper tends to minimizelosses in a gradual conical expansion region.

Referring to FIGS. 42–45, it can be seen that other conduitconfigurations can result in advantageous flow resistance. These conduitdesigns may or may not embody the design characteristics of the conduit1400 of FIG. 41. For example, shown in FIG. 42 is a schematic view of acurved conduit 1430, similar to that of FIG. 41, except having a spiralflow path 1434 therethrough. This spiral flow path 1434 increases theresistance to negative or diastolic flow. By the same token, duringsystole, the pressures available are sufficient to overcome theresistance presented by the spiral flow path 1434. In this case, theconduit 1430 may be of solid configuration and having a spiral flow pathcut or bored therethrough. On the other hand, the conduit 1430 may bemanufactured in a spiral fashion comprising a hollow flow path throughthe spiral.

Similarly, as shown in FIG. 43, there is shown a conduit 1440 with ahelical flow path 1444. Again, this conduit 1440 takes advantage of theincreased flow resistance in the negative or reverse flow directionduring diastole. The side walls of these conduits may be straight ortapered, as shown in FIG. 41, to further effect the degree ofresistance. Thus, not only does the blood flow see a larger pressuredifferential between the vessel and the ventricle, but it may also seean increasing pressure due to a gradually tapered, smaller diameterblood flow path in the reverse direction. Again, however, this designmay be reversed (in order to increase forward resistance) where only apartial occlusion is presented.

FIGS. 44A–44C utilize an alternate method of flow resistance whichcomprises a type of fluidic vortex diode. Referring to FIG. 44A, thereis shown a conduit 1450 having an entrance 1454 and an exit 1458. Itwill be appreciated that the entrance 1454 and exit 1458 can bepositioned in the ventricle LV and coronary artery CA, respectively, andthat this illustration is only schematic with respect to the placementof the conduit 1450 in the heart tissues of the patient. Furthermore, asdiscussed above, the entrance 1454 and exit 1458 may be placed in theventricle LV and coronary artery CA, respectively, or vice versa,depending upon patient indications and the desired flow optimization.Thus, it is convenient with respect to FIGS. 44A and 44B to discuss themin terms of a high resistance direction (shown in FIG. 44A) and a lowresistance direction (shown in FIG. 44B). Both such flow resistances areachieved in a single device by providing a chamber or housing(preferably circular) with a tangential flow port and a central axialflow port. If the direction of flow is such that fluid enters thetangential flow port and exits the axial flow port, as shown in FIG.44A, a vortex 1462 is created in the circular chamber. This vortex 1462greatly impedes the flow of fluid through the device and provides for ahigh resistance fluid flow conduit. The fluid dynamics behind thisresult are such that the rotation of the fluid in the chamber generatescentrifugal forces that cause the fluid to push outward toward theperiphery of the chamber. Since fluid is entering the chamber at theperiphery where the resulting centrifugal forces react, the outward pushof the rotating fluid impedes the flow.

When the flow direction is reversed, such as that shown in FIG. 44B,fluid flows into the chamber 1468 from the central axial flow port 1472and from there to the tangential flow port 1476. However, no vortex iscreated. Thus, the resistance of conduit 1450 to the flow of fluid inthis direction is relatively low.

A conduit 1480 utilizing this type of vortex diode device is shown inFIG. 44C. Thus, in this embodiment, the tangential flow port 1484 isplaced in the coronary artery CA such that a high resistance to reverseflow is generated. On the other hand, the entrance 1486 to the axialflow port is placed in the ventricle LV so that blood flow into theconduit 1480 sees low resistance.

FIG. 45 illustrates an alternate embodiment of a conduit 1490 utilizingflow resistance. In this case, the conduit 1490 is in the nature of atesla valvular conduit. The geometry of the flow path in this device issuch that flow entering the conduit 1490 from one direction 1494, whichis generally likely to occur during diastole, is bifurcated at severallocations with part of the flow being conducted into passages 1496, 1498that redirect portions of the flow back into the main flow stream 1494in a direction 1500 that is essentially reversed to the direction 1494of the main flow stream. This reversed direction 1500 flow impedes themain flow stream 1494 and sets up a high resistance to fluid flow. Onthe other hand, when fluid enters in the opposite direction 1502, suchas is likely to occur during systole, no such bifurcation and noresulting flow impedance occurs. Thus, as shown in FIG. 45, the higherresistance flow direction is from the coronary artery CA toward theventricle LV. Flow in that direction 1494 experiences at least twobifurcations 1496 a, 1498 a with resulting reverse flow 1500 to impedediastolic blood flow. On the other hand, flow 1502 from the ventricle LVtoward the coronary CA does not experience any bifurcations, thusresulting in lower flow resistance.

Conduits with Proximal Extensions

As discussed above, flow resistance in the direction of ventricle LV tocoronary artery CA can be reduced by an increased exit diameter at theconduit distal portion which opens into the coronary artery CA. At thislocation, a conduit exit diameter which approximates or matches thediameter of the coronary will result in decreased flow losses andminimize flow resistance. Due to the curvature of the conduit, the flowat the conduit exit is approximately parallel to the axial flow in thecoronary. Thus, this distal conduit portion may serve not only as anadvantageous controller of the flow, but the extension nature of thedistal portion can also serve to anchor or support the conduit in itsposition. Furthermore, as noted above, this distal portion of theconduit can be designed to allow proximal flow past a partial occlusion,past the distal portion of the conduit, and into the lower coronaryregions for profusion of the heart.

Thus, referring to FIG. 46, there is shown a schematic, partialcross-sectional view of a curved conduit 1600 having an extensionportion 1604 at its proximal end (to take into consideration changes inmyocardial thickness) and a distal extension 1608 at the conduit distalend extending into the coronary artery CA. Besides minimizing flowlosses and anchoring the conduit 1600 in place, this distal extension1608 also reduces trauma to the coronary artery CA by directing flowdownstream in a substantially parallel direction.

The conduit 1600 of FIG. 46 may be installed in one embodiment, inaccordance with FIGS. 47A–D. Thus, with reference to FIG. 47A, thecurved tubular conduit 1600 may have a sharpened or pointed proximal tip1612 to allow it to penetrate the heart tissues, including at least thecoronary artery CA and the myocardium HW so that the proximal endextends into the ventricle LV, as shown in FIG. 47B. The curved conduit1600 is advanced in a rotational or curved fashion, as shown in FIG.47C, so that it extends well into the ventricle LV. In fact, the conduit1600 can be of such a length and constructed from a material to allow itto bend and curve into the coronary artery CA in a downstream fashion,as shown in FIG. 47C. Thus, the curved conduit 1600 actually is placedso as to bypass its final destination to allow it to be curved and theninserted in a downstream fashion as shown in FIG. 47D.

An alternate embodiment of the conduit 1600 of FIG. 46 is shown in FIG.48. In this case, the hollow, curved, tubular conduit 1630 is providedwith an atraumatic ball configuration 1634 at the distal end of theconduit 1630. This configuration allows for reduced flow losses at theexit, while at the same time providing a proximal extension whichsecures the conduit 1630 in place without damaging the sensitive liningsof the vessel. Alternatively, the neck of the conduit 1630 just proximalthe end having the atraumatic ball 1634 provides a location for ananchoring suture or tether 1638, as shown in FIG. 48. The proximal endof the conduit 1630 can be provided with a non-coring, deflective point1642, and the tubular section 1646 can be constructed from a surgeon'sneedle having a ⅜ inch radius of curvature. As with all the conduitsdepicted herein, they can be installed in a variety of vascular orsurgical procedures, depending upon patient indications. Thus, theconduit 1630 of FIG. 48 may be implanted in the manner illustrated inFIGS. 47A–47D. Alternatively, it may be inserted by means of a curvedtrocar or stylet, or may even travel over a thin guidewire. The conduit1630 may be constructed from a rigid or semi-rigid material, it may havesolid walls or a lattice stent-like construction as discussed below.

FIG. 48A illustrates the conduit 1630 of FIG. 48 in its uninstalledcondition. FIGS. 48B–C illustrate alternate embodiments in which theatraumatic ball end at the distal end of the conduit 1630 is replacedwith a partial ball 1650 or semi-spherical section, shown in FIG. 48B,or a flange-type structure 1654 as shown in FIG. 48C.

Another embodiment of a conduit 1670 having a proximal extension isshown in FIG. 49. In this case, the proximal portion 1674 of the conduit1670 and the main body 1678 portion thereof which extends to themyocardium HW are relatively stiff or rigid regions. These portions ofthe conduit 1670 can be constructed from a smooth material, such as ametallic stainless steel or nitinol hypotube. Thus, a laminar flowpattern is generated in the conduit 1670 in these regions.

On the other hand, as the flow approaches the artery CA, the conduit1670 can be constructed from a combination of laser cut hypotube andelastomer to provide a flexible distal portion which extends proximallyinto the coronary artery CA. In the embodiment of FIG. 49, the curvedsection of the conduit 1670 is stent-like or is of a latticeconstruction. It can be manufactured by laser cutting of a nitinolhypotube with elastomeric sections joining the lattice portions. Theproximal extension 1674 may comprise at least a unitary arm with acircular flow exit 1682, as illustrated in FIG. 49.

Alternatively, as shown in FIGS. 50A–50C, the conduit of FIG. 49 can beconstructed so that it is substantially entirely of a latticeconstruction or stent-like. In this case, the term stent-like is used torefer to coronary stents which are often implanted followingangioplasty, and is thus in an illustrated manner only and not to berestrictive in any sense of the term. Thus, as shown in FIG. 50A, thereis a conduit 1690 having a solid or smooth proximal end 1694 whichextends into the ventricle LV and a main body section 1698 which is of alattice-type construction. This section likewise can be constructed fromthe laser cutting or other cutting of a nitinol hypotube or othermaterial. FIG. 50B illustrates the conduit 1690 of FIG. 50A prior tohaving its distal portion 1702 bent so as to extend into the distalregions of the coronary artery CA. FIG. 50C, on the other hand,illustrates the conduit 1690 of FIG. 50A as installed in the hearttissues with the distal portion 1702 curved so as to align with thecoronary artery CA.

The lattice construction of the conduit 1690 of FIGS. 50A–C may beconstructed from a variety of materials. FIGS. 51A–51D illustratevarious constructions for the conduit 1690 in FIG. 50, which includes asingle arm with an opening at its end. In each case, the conduit 1690 iscomprised essentially of a tapered or pointed proximal section 1694which extends into the ventricle LV, a main body 1698 of a latticeconstruction, and an extension arm 1706 and distal anchor 1710 whichextends into the coronary artery CA. The distal extension arm 1706 andexit portion can take on a variety of shapes as shown in FIGS. 51A–51D.These conduits 1690 can be constructed, preferably, from a nitinoltubing of approximately 0.060 inches in outer diameter with an innerdiameter of approximately 0.048 inches. Another advantage of theseconduits 1690 is their flexibility in the main body region 1698 inresponse to changes in myocardial thickness. Also, due to the latticeconstruction at the distal end, proximal flow through the coronary CA isnot impeded.

FIG. 52 illustrates an alternate embodiment 1716 with a distal extension1720 extending both distally in the coronary artery CA as well asproximally. Thus, the distal portion 1720 of the conduit 1716 has aT-like configuration. As shown in FIG. 52, this T-like distal portion1720 of the conduit 1716 may have a lattice construction such as theconduit 1690 shown in FIGS. 50 and 51. The main body 1724 of the conduit1716 of FIG. 52 may be a smooth tubular structure, or may be of alattice construction as shown in FIGS. 50 and 51.

The conduit 1730 of FIG. 53 has an articulating distal portion 1734which may fold down either in a manner so as to either extend distallywith respect to the coronary artery CA or proximally, as shown in FIG.53. In this case, the distal extension 1734 of the conduit 1730 ispreferably of a lattice construction made from a nitinol hypotube asdiscussed above. This distal portion 1734 is designed to collapseagainst the main body 1738 of the conduit 1730 for insertion and thenextend to an approximately 90° position, as shown in FIG. 53, within thecoronary lumen after insertion. Thus, the distal portion 1734 of theconduit 1730 serves as an articulating or anchor arm for positioning thedevice within the heart tissues.

FIG. 54 illustrates an alternate embodiment 1750 having an elastomericdistal anchoring arm 1754 for the conduit 1750. In this case, the distalportion of the conduit 1750 is provided with a sealing portion 1758 anda shoulder portion 1762. Both of these may preferably be constructedfrom elastomeric material or some other soft material. The sealingportion 1758 extends through a hole in the coronary artery CA which isused to implant the conduit 1750 of FIG. 54. The shoulder portion 1762supports the sealing portion 1758 and seals the opening against thecoronary wall. The distal portion of the conduit 1750 itself may beconstructed from a metallic or other flexible material such that thebias or bending characteristic of the conduit 1750 causes it to pushslightly at the distal end against the coronary wall, thus providing theseal.

The bypass devices and methods herein provide significant improvementsin the treatment of vascular blockages. It should be understood thatwhile various anatomical features have been discussed herein for ease ofreference, the anastomosis devices described herein can also be used inconnection with vessels other than coronary artery, etc. Thus, it isintended that the present invention is applicable to a wide range ofuses where vascular anastomosis is indicated. It is further intendedthat the present invention may applicable during a wide variety ofsurgical techniques, from conventional sternotomy or “open chest”procedures, to minimally-invasive direct coronary artery bypass (MIDCAB)and even vascular approaches.

Accordingly, it is to be understood that the drawings and descriptionsherein are proffered by way of example to facilitate comprehension ofthe invention and should not be construed to limit the scope thereof.

1. A method of providing direct blood flow between a heart chamber and acoronary vessel, the method comprising the steps of: inserting aninstrument through an anterior wall of the coronary vessel; furtherinserting the instrument through a posterior wall of the coronary vesseland a heart wall between the heart chamber and the coronary vessel toform a passageway in the heart wall; and radially expanding an implantwithin the passageway.
 2. The method of claim 1, further comprisingadvancing the implant past the posterior wall of the coronary vessel andinto the passageway.
 3. The method of claim 2, further comprisingadvancing the implant past the anterior wall of the coronary vessel. 4.The method of claim 1, further comprising inserting the implant in thepassageway via a catheter.
 5. The method of claim 4, further comprisingadvancing the catheter to the passageway via the heart chamber.
 6. Themethod of claim 1, wherein expanding the implant includes expanding animplant carrying a substance for delivery to the heart wall.
 7. Themethod of claim 6, wherein the substance is chosen from angiogenesisfactors and nucleic acid instructions for angiogensis factors.
 8. Themethod of claim 6, wherein the substance is for at least one ofgenerating, stimulating, and enhancing blood vessel formation.
 9. Themethod of claim 1, wherein the implant includes a stent.
 10. The methodof claim 1, wherein expanding the implant includes expanding the implantfrom a collapsed configuration.
 11. The method of claim 1, wherein thepassageway in the heart wall is formed via one of lasing, drilling, andboring.
 12. The method of claim 1, wherein inserting the instrumentincludes inserting an incising instrument.
 13. The method of claim 1,further comprising removing the instrument from the heart wall prior toexpanding the implant in the passageway.
 14. The method of claim 1,wherein the implant does not extend substantially along an axialdirection of the vessel.